# Asterisk Project : AMI 1.4 Specification

Added by mjordan , edited by mjordan on Aug 28, 2013

This Specification is still in draft form.

# 1. Introduction

This Asterisk Manager Interface (AMI) specification describes the relationship between Asterisk and an external entity wishing to communicate with Asterisk over the AMI protocol. It describes:

- An overview of the AMI protocol
- The operations AMI provides external entities wishing to control Asterisk
- Basic formatting of AMI message structures
- Guaranteed operations, configuration control, and other information provided by Asterisk in AMI 1.4

## 1.1. Scope

This specification describes AMI version 1.4 for Asterisk 12. This specification provides details on the functional, operational and design requirements for AMI 1.4. Note that this does not include a comprehensive listing of the AMI configuration file parameters or messages that a system interfacing over AMI in Asterisk 12 will send/receive; however, it does provide a baseline of the supported features and messages provided in AMI 1.4. This specification should be used in conjunction with the documented AMI actions and events in Asterisk 12 to encompass the full range of functionality provided by AMI in Asterisk 12.

In addition, this specification provides interface requirements levied on AMI by Stasis Core. It conveys sufficient detail to understand how AMI attaches to Stasis Core and interacts with other entities on the Stasis Core message bus.

This specification is intended for all parties requiring such information, including software developers, system designers and testers responsible for implementing the interface.

# 2. Terminology

Term | Definition
--- | ---
Action | A command issued to Asterisk from an external entity via AMI
Client | An external entity communicating with Asterisk via AMI over some transport mechanism
Event | A message sent from Asterisk to an external entity via AMI
Field | A key/value pair that exists in either an action or event
Stasis-Core | The internal framework that AMI is built on top of

# 3. Protocol Overview

Asterisk provides a number of interfaces that serve different purposes. Say, for example, we wanted to manipulate a call between Alice and Bob via some external mechanism. Depending on what we wanted to do with the call, we may use one or more interfaces to manipulate the channels that make up the call between Alice and Bob.

Alice calls Bob and... | Interface
--- | ---
... we want to use a local script to execute some logic on Alice's channel | AGI
... we want to execute a script on a remote machine on Bob's channel | FastAGI
... we want to put Alice into an IVR with fine grained media control, where the IVR is written outside of `extensions.conf` | ExternalIVR
... we want to control Alice and Bob's underlying channel objects | AMI (with, possibly, AsyncAGI as well)

In general, AMI is used to manage Asterisk and its channels. It does not determine what actions are executed on a particular channel - the dialplan and some AGI interface does that - but it does allow a client to control call generation, aspects of call flow, and other internals of Asterisk.

At its heart, AMI is an asynchronous message bus: it spills events that contain information about the Asterisk system over some transport. In response, clients may request that Asterisk takes some action. These two concepts - actions and events - make up the core of what is AMI. As AMI is asynchronous, as events occur in Asterisk they are immediately sent to the clients. This means that actions issued by entities happen without any synchronization with the events being received, even if those events occur in response to an action. It is the responsibility of entities to associate event responses back to actions.

Clients wishing to use AMI act as clients and connect to Asterisk's AMI server over a supported transport mechanism. Authentication may or may not be enabled, depending on the configuration. Once connected, events can be automatically spilled to the connected clients, or limited in a variety of fashions. A connected client can send an action to the AMI server at any time. Depending on the allowed authorizations, the action may be allowed or disallowed.

More information on the various ways a client can be configured can be seen in AMI Configuration.

Sometimes, the term command may be used instead of the term action. With respect to AMI actions, command is synonymous with action, and the two can be treated the same. For the sake of consistency, we've attempted to use the term action where possible.

Historically, AMI has existed in Asterisk as its own core component `manager`. AMI events were raised throughout Asterisk encoded in an AMI specific format, and AMI actions were processed and passed to the functions that implemented the logic. In Asterisk 12, AMI has been refactored to sit on top of Stasis Core, which is a generic, protocol independent message bus internal to Asterisk. From the perspective of clients wishing to communicate with Asterisk over AMI very little has changed; internally, the Stasis representation affords a much higher degree of flexibility with how messages move through Asterisk.

Asterisk's Stasis-Core provides a generic publish/subscribe message bus inside of Asterisk. While AMI often directly interacts with constructs in Asterisk through actions, it receives its events through messages published over Stasis-Core. It translates the generic Stasis messages into an AMI event, and sends those to the appropriate AMI clients.

# 4. Semantics and Syntax

## 4.1. Message Sending and Receiving

By default, AMI is an asynchronous protocol that sends events immediately to clients when those events are available. Likewise, clients are free to send actions to AMI at any time, which may or may not trigger additional events. The exception to this is when the connection is over HTTP/HTTPS; in that scenario, events are only transmitted as part of the response to an HTTP POST.

Various options for configuration of clients can control which events are sent to a client. Events can be whitelisted/blacklisted explicitly via event filters, or implicitly by class authorizations.

## 4.2. Message Layout

AMI is an ASCII protocol that provides bidirectional communication with clients. Each field in an AMI message - action or event - is delineated by the '\r\n' characters. An action or event is terminated by an additional '\r\n' character. Within a message, each field is a key value pair delineated by a ':'. A single space MUST follow the ':' and precede the value.

    Event: Newchannel
    Privilege: call,all
    Channel: SIP/misspiggy-00000001
    Uniqueid: 1368479157.3
    ChannelState: 3
    ChannelStateDesc: Up
    CallerIDNum: 657-5309
    CallerIDName: Miss Piggy
    ConnectedLineName:
    ConnectedLineNum:
    AccountCode: Pork
    Priority: 1
    Exten: 31337
    Context: inbound

This is syntantically equivalent to the following ASCII string:

    Event: Newchannel\r\nPrivilege: call,all\r\nChannel: SIP/misspiggy-00000001\r\n
    Uniqueid: 1368479157.3\r\nChannelState: 3\r\n
    ChannelStateDesc: Up\r\nCallerIDNum: 657-5309\r\n
    CallerIDName: Miss Piggy\r\nConnectedLineName:\r\nConnectedLineNum:\r\nAccountCode: Pork\r\n
    Priority:\r\nExten: 31337\r\nContext: inbound\r\n\r\n

Actions are specified in a similar manner. Note that depending on the message, some keys can be repeated.

    Action: Originate
    ActionId: SDY4-12837-123878782
    Channel: SIP/kermit
    Context: outbound
    Exten: s
    Priority: 1
    CallerID: "Kermit the Frog" <123-4567>
    Account: FrogLegs
    Variable: MY_VAR=frogs
    Variable: HIDE_FROM_CHEF=true

In addition, no ordering is implied on message specific keys. Hence, the following two messages are semantically the same.

    Action: Originate
    ActionId: SDY4-12837-123878782
    Channel: SIP/kermit
    Context: outbound
    Exten: s
    Priority: 1
    CallerID: "Kermit the Frog" <123-4567>
    Account: FrogLegs
    Variable: MY_VAR=frogs
    Variable: HIDE_FROM_CHEF=true

    ActionId: SDY4-12837-123878782
    Action: Originate
    Variable: HIDE_FROM_CHEF=true
    Variable: MY_VAR=frogs
    Channel: SIP/kermit
    Account: FrogLegs
    Context: outbound
    Exten: s
    CallerID: "Kermit the Frog" <123-4567>
    Priority: 1

This is also true for events, although by convention, the `Event` key is the first key in the event. If an action or event contains duplicate keys, such as `Variable`, the order in which Asterisk processes said keys is the order in which they occur within the action or event.

Keys are case insensitive. Hence, the following keys are equivalent:

    Action: Originate

    ACTION: Originate

    action: Originate

The case sensitivity for values is left up to the context in which they are interpreted.

### 4.2.1. Common Fields

#### 4.2.1.1. Actions

##### 4.2.1.1.1. General Fields

This section lists fields that apply generally to all actions.

###### 4.2.1.1.1.1. Action

Action specifies the action to execute within Asterisk. Each value corresponds to a unique action to execute within Asterisk. The value of the Action field determines the allowed fields within the rest of the message. By convention, the first field in any action is the Action field.

###### 4.2.1.1.1.2. ActionId

ActionId is a universal unique identifier that can optionally be provided with an action. If provided in an action, events that are related to that action will contain the same ActionId value, allowing a client to associate actions with events that were caused by that action.

It is recommended that clients always provide an ActionId for each action they submit.

##### 4.2.1.1.2. Channels

This section lists fields that apply generally to all actions that interact upon an Asterisk channel. Note that an Action that interacts with a channel must typically supply the Channel field.

Upgrade Tip

In the past, AMI clients would have to contend with channel rename events. As Asterisk will now not change the name of a channel during its lifetime, this is no longer necessary.

###### 4.2.1.1.2.1. Channel

The Asterisk channel name. A channel name is provided by AMI to clients during a Newchannel event. A channel name can be viewed as the handle to a channel.

###### 4.2.1.1.2.2. Uniqueid

A universal unique identifier for the channel. In systems with multiple Asterisk instances, this field can be used to construct a globally unique identifier for a channel, as a channel name may occur multiple times across Asterisk instances.

#### 4.2.1.2. Events

##### 4.2.1.2.1. General Fields

This section lists fields that apply generally to all events.

###### 4.2.1.2.1.1. Event

The unique name of the event being raised. The value of the Event field determines the rest of the contents of the message. By convention, the Event field is the first field in an AMI message.

###### 4.2.1.2.1.2. ActionId

If present, the Action's corresponding ActionId that caused this event to be created. If an Action contained an ActionId, any event relating the success or failure of that action MUST contain an ActionId field with the same value.

###### 4.2.1.2.1.3. Privilege

The class authorizations associated with this particular event. The class authorizations for a particular event are in a comma-delineated list. For more information, see class authorizations.

##### 4.2.1.2.2. Channels

This section lists fields that apply generally to all events that occur due to interactions upon an Asterisk channel.
Events that relate multiple channels will prefix these fields with an event specific role specifier. For example, a DialBegin or a DialEnd event will prefix the outbound channel's fields with Dest. So, the Channel field is the DestChannel field; the Uniqueid field is the DestUniqueid field, etc.

###### 4.2.1.2.2.1. Channel

The current Asterisk channel name. This corresponds to the Channel field in actions.

###### 4.2.1.2.2.2. Uniqueid

A universal unique identifier for the channel. This corresponds to the Uniqueid field in actions.

###### 4.2.1.2.2.3. ChannelState

The current state of the channel, represented as an integer value. The valid values are:

Value | State | Description
--- | --- | ---
0 | Down | Channel is down and available
1 | Rsrvd | Channel is down, but reserved
2 | OffHook | Channel is off hook
3 | Dialing | The channel is in the midst of a dialing operation
4 | Ring | The channel is ringing
5 | Ringing | The remote endpoint is ringing. Note that for many channel technologies, this is the same as Ring.
6 | Up | A communication path is established between the endpoint and Asterisk
7 | Busy | A busy indication has occurred on the channel
8 | Dialing Offhook | Digits (or equivalent) have been dialed while offhook
9 | Pre-ring | The channel technology has detected an incoming call and is waiting for a ringing indication
10 | Unknown | The channel is an unknown state

Depending on the underlying channel technology, not all states will be used. Channels typically begin in either the Down or Up states.

###### 4.2.1.2.2.4. ChannelStateDesc

The text description of the channel state. This will be one of the State descriptions in the table in ChannelState.

###### 4.2.1.2.2.5. CallerIDNum

The current caller ID number. If the caller ID number is not known, the string "<unknown>" is returned instead.

###### 4.2.1.2.2.6. CallerIDName

The current caller ID name. If the caller ID name is not known, the string "<unknown>" is returned instead.

###### 4.2.1.2.2.7. ConnectedLineNum

The current connected line number. If the connected line number is not known, the string "<unknown>" is returned instead.

###### 4.2.1.2.2.8. ConnectedLineName

The current connected line name. If the connected line name is not known, the string "<unknown>" is returned instead.

###### 4.2.1.2.2.9. AccountCode

The channel's accountcode.

###### 4.2.1.2.2.10. Context

The current context in the dialplan that the channel is executing in.

###### 4.2.1.2.2.11. Exten

The current extension in the dialplan that the channel is executing in.

###### 4.2.1.2.2.12. Priority

The current priority of the current context, extension in the dialplan that the channel is executing in.

###### 4.2.1.2.2.13. ChanVariable

Channel variables specific to a channel can be conveyed in each AMI event related to that channel. When this occurs, each variable is referenced in a ChanVariable field. The value of a ChanVariable field will always be of the form `key=value`, where `key` is the name of the channel variable and `value` is its value.

##### 4.2.1.2.3. Bridges

###### 4.2.1.2.3.1. BridgeUniqueid

A unique identifier for the bridge, which provides a handle to actions that manipulate bridges.

###### 4.2.1.2.3.2. Bridgetype

The type of the bridge. Bridge types can vary based on the registered bridge technologies; in general, however, this will indicate whether the bridge is a holding bridge, a simple two-party bridge, or a multi-party bridge. The type of a bridge can change during the lifetime of the bridge as channels enter and leave a bridge.

##### 4.2.1.2.4. Action Responses

When an Action is submitted to AMI, the success or failure of the action is communicated in subsequent events.

###### 4.2.1.2.4.1. Response

Contains whether or not the action succeeded or failed. Valid values are "Success" or "Error". Events that are in response to an action MUST include this field.

###### 4.2.1.2.4.2. EventList

Some actions will cause a chain of events to be created. Events that are a response to an action that causes such a sequence will contain the EventList field with a value of "start". When all generated events have been sent, a final event will be sent containing the EventList field with the value "complete".

If, for some reason, an error occurs and the events cannot be sent, an event will be sent with an EventList field that contains the value "cancelled".

Note that the events that mark the completion or cancellation of an event list are not technically action responses, and have their own specific event types.

###### 4.2.1.2.4.3. Message

An optional text message that provides additional contextual information regarding the success or failure of the action.

## 4.3. Actions

The supported actions for Asterisk 12 are listed here:

Asterisk 12 AMI Actions

While new AMI Actions may be added over the lifetime of Asterisk 12, existing AMI Actions will not be removed.

## 4.4. Events

The supported events for Asterisk 12 are listed here:

Asterisk 12 AMI Events

While new AMI Events may be added over the lifetime of Asterisk 12, existing AMI Events will not be removed.

## 4.5. Channel Interaction/Lifetime

While channels are independent of AMI, they have a large implication on the events sent out over AMI. Many of the events in AMI correspond to changes in channel state. While AMI is an asynchronous protocol, there is some ordering with respect to the events that are relayed for a particular channel. This section provides the basic event relationships that are guaranteed through AMI.

### 4.5.1. Basic Channel Lifetime

All channels begin with a Newchannel event. A Newchannel will always contain the following fields:

- The current Channel name that acts as a handle to the channel for that channel's lifetime for a single Asterisk system
- The Uniqueid for the channel, that allows systems to have a globally unique identifier for the channel

Changes in the state of the channel, i.e., the ChannelState field, are conveyed via Newstate events.
Notification of a Channel being disposed of occurs via a Hangup event. A Hangup signals the termination of the channel associated with the Uniqueid. After the Hangup event, no further events will be raised in relation to the channel with that Uniqueid, and the communication between the endpoint and Asterisk via that channel is terminated.

Example

    Event: Newchannel
    Privilege: dialplan,all
    Channel: SIP/kermit-00000001
    Uniqueid: asterisk-1368479157.1
    ChannelState: 0
    ChannelStateDesc: Down
    ...
| Kermit the Frog's SIP channel is created. The is the first event for `SIP/kermit-00000001` and indicates a path of communication being opened up between Asterisk and Kermit's SIP device.
    Event: Newstate
    Privilege: dialplan,all
    Channel: SIP/kermit-00000001
    Uniqueid: asterisk-1368479157.1
    ChannelState: 6
    ChannelStateDesc: Up
    ...
| Kermit the Frog's SIP channel's state changes from Down to Up
    Event: Hangup
    Privilege: dialplan,all
    Channel: SIP/kermit-00000001
    Uniqueid: asterisk-1368479157.1
    ChannelState: 6
    ChannelStateDesc: Up
    Cause: 16
    Cause-txt: Normal Clearing
    ...
| Kermit the Frog's SIP channel is hung up. At this point, no further events for `SIP/kermit-00000001` will be sent.

### 4.5.2. Channel Variables

For each channel variable that is changed, a VarSet event is sent to the client. The VarSet event contains the new value of the appropriate channel variable. Note that channel variables can also be conveyed in ChanVariable fields.

### 4.5.3. DTMF

DTMF is indicated via a DTMFBegin/DTMFEnd events. A DTMFEnd event MUST convey the duration of the DTMF tone in milliseconds.

Behavioral Change Warning

The combination of DTMFBegin/DTMFEnd events replaces the removed DTMF event.

### 4.5.4. Dialplan Execution

As a channel executes operations in the dialplan, those operations are conveyed via a NewExten event. Each transition to a new combination of context, extension, and priority will trigger a NewExten event.

Example

    Event: Newexten
    Privilege: dialplan,all
    Channel: SIP/kermit-00000001
    Uniqueid: asterisk-1368479157.1
    ...
    Context: default
    Extension: h
    Priority: 1
    Application: NoOp
    AppData: Ah Snap
| Kermit the Frog's SIP channel has been hung up, and he's been tossed rudely into the h extension. This event informs the clients that Kermit's channel is in context default, extension h, priority 1, and is about to execute the NoOp application with application data "Ah Snap".

### 4.5.5. Dialing and Origination

Dial operations always result in two events: a DialBegin event that signals the beginning of the dial to a particular destination, and a DialEnd event that signals the end of the dialing. In parallel dialing situations, DialBegin/DialEnd events MUST be sent for each channel dialed. For each DialBegin event sent, there MUST be a corresponding DialEnd event.

In dialing situations with a caller and a called party, the DialBegin and DialEnd events convey information about both channels. The calling channel uses the standard channel field names, while the called party's field names are prefixed with "Dest". In dialing situations where there is no caller, such as when Asterisk originates an outbound call via a call file, only the called channel is represented in the events. The channel field names are still prefixed with "Dest" in this case.
A DialEnd occurs whenever Asterisk knows the final state of the channel that it was attempting to establish. This is communicated in the DialStatus field.

Behavioral Change Warning

The pair of DialBegin/DialEnd events replaces the deprecated Dial event. Note that the Dial event signalling the end of dialing would not normally be sent until after bridging was complete; this operation should now occur when the dial operation has determined the status of a particular called channel.

Simple Successful Dial

    Event: Newchannel
    Channel: SIP/animal-00000002
    Uniqueid: asterisk-1368479160.5
    ...
    Event: DialBegin
    Channel: SIP/kermit-00000001
    Uniqueid: asterisk-1368479155.1
    DestChannel: SIP/animal-00000002
    DestUniqueid: asterisk-1368479160.5
    ...
    Event: DialEnd
    Channel: SIP/kermit-00000001
    Uniqueid: asterisk-1368479155.1
    DestChannel: SIP/animal-00000002
    DestUniqueid: asterisk-1368479160.5
    DialStatus: ANSWER
    ...
| In this example, Kermit decides to dial Animal. A new channel between Asterisk and Animal's SIP device is created and conveyed via a Newchannel event, and then a dial operation is begun. Note that in the DialBegin event, Kermit's SIP device is the caller as he initiated the dial operation, while Animal's SIP device is the destination. As such, the fields referring to Animal's SIP channel are prefixed with "Dest". When Animal eats his handset (causing the device to think he merely took it off the hook), the SIP device answers and the dial operation completes. This indicated by a DialEnd event. At this point, the channel is ready for something - it can execute in the dialplan, or be immediately bridged with the calling channel.

Simple Failed Dial

    Event: Newchannel
    Channel: SIP/animal-00000003
    Uniqueid: asterisk-1368479199.1
    ...
    Event: DialBegin
    Channel: SIP/kermit-00000001
    Uniqueid: asterisk-1368479150.1
    DestChannel: SIP/animal-00000003
    DestUniqueid: asterisk-1368479199.1
    ...
    Event: DialEnd
    Channel: SIP/kermit-00000001
    Uniqueid: asterisk-1368479150.1
    DestChannel: SIP/animal-00000003
    DestUniqueid: asterisk-1368479199.1
    DialStatus: TIMEDOUT
    ...
    Event: Hangup
    Channel: SIP/animal-00000003
    Uniqueid: asterisk-1368479199.1
    ...
| In this example, we decide to dial Animal again. Unfortunately, Animal ate his handset, so we inevitably time out. When we do, a DialEnd event indicates the failure condition in the DialStatus field.

Parallel Dial

    Event: Newchannel
    Channel: SIP/animal-00000003
    Uniqueid: asterisk-1368479150.3
    ...
    Event: Newchannel
    Channel: SIP/drteeth-00000004
    Uniqueid: asterisk-1368479150.4
    ...
    Event: DialBegin
    Channel: SIP/kermit-00000001
    Uniqueid: asterisk-1368479150.0
    DestChannel: SIP/animal-00000003
    DestUniqueid: asterisk-1368479150.3
    ...
    Event: DialBegin
    Channel: SIP/kermit-00000001
    Uniqueid: asterisk-1368479150.0
    DestChannel: SIP/drteeth-00000004
    DestUniqueid: asterisk-1368479150.4
    ...
    Event: DialEnd
    Channel: SIP/kermit-00000001
    Uniqueid: asterisk-1368479150.0
    DestChannel: SIP/drteeth-00000004
    DestUniqueid: 5asterisk-1368479150.4
    DialStatus: ANSWER
    ...
    Event: DialEnd
    Channel: SIP/kermit-00000001
    Uniqueid: asterisk-1368479150.0
    DestChannel: SIP/animal-00000003
    DestUniqueid: asterisk-1368479150.3
    DialStatus: CANCEL
    ...
| In this example, Kermit decides to dial Animal and Dr. Teeth. Dr. Teeth immediately answers, and so we cancel the dial to Animal. We can now do something with Dr. Teeth's channel (such as bridge him with his dentist) - however, Animal's channel is implicitly destroyed, as his device never answered.

### 4.5.6. Bridging

A bridge contains 0 or more channels. When a channel is in a bridge, it has the potential to communicate with other channels within the bridge. Before channels enter a bridge, a BridgeCreate event is sent, indicating that a bridge has been created. When a bridge is destroyed, a BridgeDestroy event is sent. All channels within a bridge must leave a bridge prior to the BridgeDestroy event being sent.

When a channel enters a bridge, a BridgeEnter event is raised. When a channel is put into a bridge, it is implied that the channel can pass media between other channels in the bridge. This is not guaranteed, as other properties on the channel or bridge may restrict media flow. For example, bridges of the "holding type" implicitly restrict the media flow between channels. Likewise, media may be restricted in multi-party conference bridges based on user role permissions, such as when a conference leader mutes all participants in a conference. The BridgeEnter event does indicate, however, that a potential relationship between channels in a bridge exists.
When a channel leaves a bridge, a corresponding BridgeLeave event is raised. A BridgeLeave event MUST mean that the channel that left the bridge can no longer pass media to other channels still in the bridge. This does not necessarily mean that the channel is being hung up; rather, that it is no longer in a communication path with some other set of channels.

In all cases, if a channel has a BridgeEnter event, it MUST have a corresponding BridgeLeave event. If a channel is hung up and it is in a bridge, a BridgeLeave event MUST precede the Hangup event.

If a transfer operation begins, a Transfer event MUST be raised for the channels involved in the transfer prior to those channels leaving the bridge or entering another bridge. Similarly, if a channel enters a parking lot, a ParkedCall event MUST be raised for the channel prior to it entering the bridge that represents the parking lot.

If a property of a bridge is changed, such as the type going from a simple two-party bridge to a multi-party bridge, then the BridgeUpdate event is sent with the updated parameters.

#### 4.5.6.1. Two Party Bridging

Parties are bridged by virtue of them entering a bridge, as indicated by a BridgeEnter. When parties are no longer talking, a BridgeLeave event is sent for each channel that leaves the bridge.

Example - Two Party Bridge

    Event: BridgeCreate
    Bridgetype: core
    BridgeUniqueid: 1234
    ...
    Event: BridgeEnter
    Bridgetype: core
    BridgeUniqueid: 1234
    Channel: SIP/kermit-00000001
    Uniqueid: asterisk-1368479150.0
    ...
| Kermit the Frog's SIP channel enters into Bridge 1234. As a result, the bridge is first created (denoted by the BridgeCreate event), and then Kermit's channel enters the bridge (the BridgeEnter event)
    Event: BridgeEnter
    Bridgetype: core
    BridgeUniqueid: 1234
    Channel: SIP/gonzo-00000002
    Uniqueid: asterisk-1368479150.1
    ...
| Gonzo the Great enters the bridge and talks with Kermit. Note that the bridge Gonzo entered is Bridge 1234; by virtue of this being the same bridge Kermit entered, we know that the two can talk.
    Event: BridgeLeave
    Bridgetype: core
    BridgeUniqueid: 1234
    Channel: SIP/kermit-00000001
    Uniqueid: asterisk-1368479150.0
    ...

    Event: Hangup
    Channel: SIP/kermit-00000001
    Uniqueid: asterisk-1368479150.0
    ...
| Kermit decided he was tired of Gonzo's pontificating, and hung up on Gonzo. We are first alerted that Kermit has left the bridge; quickly thereafter, we receive the Hangup event indicating that Kermit's channel is dead.
    Event: BridgeLeave
    Bridgetype: core
    BridgeUniqueid: 1234
    Channel: SIP/gonzo-00000002
    Uniqueid: asterisk-1368479150.1
    ...

    Event: Hangup
    Channel: SIP/gonzo-00000002
    Uniqueid: asterisk-1368479150.1
    ...

    Event: BridgeDestroy
    Bridgetype: core
    BridgeUniqueid: 1234
    ...
| Asterisk is configured to not let Gonzo continue on in the dialplan once his bridge is broken. As such, Gonzo is forcibly ejected from the bridge, and is hung up on after. Because no channels are left in the bridge, the bridge is destroyed.

In this scenario, it was perfectly acceptable for either Kermit or Gonzo's channels to continue after the bridge was broken. Since this represents the most basic two-party call scenario, once one party decided to hang up, the other party was also hung up on.

#### 4.5.6.2. Transfers

Transfers begin with a Transfer event, which indicates information about the transfer that is about to take place. Subsequently, BridgeLeave/BridgeEnter events are used to indicate which channels are talking at different stages during the transfer.

Example - Blind Transfer

    Event: BridgeCreate
    Bridgetype: core
    BridgeUniqueid: 1234
    ...
    Event: BridgeEnter
    Bridgetype: core
    BridgeUniqueid: 1234
    Channel: SIP/kermit-00000001
    Uniqueid: asterisk-1368479150.0
    ...
| Kermit the Frog's SIP channel enters into Bridge 1234
    Event: BridgeEnter
    Bridgetype: core
    BridgeUniqueid: 1234
    Channel: SIP/fozzie-00000002
    Uniqueid: asterisk-1368479150.2
    ...
| Fozzie Bear's SIP channel enters into Bridge 1234. At this point, Fozzie and Kermit can talk to each other.
    Event: Transfer
    Privilege: call,all
    TransferMethod: Core
    TransferType: Blind
    Channel: SIP/fozzie-00000002
    Uniqueid: 550e8400-e29b-41d4-a716-446655440001
    TargetChannel: SIP/kermit-00000001
    TargetUniqueid: 550e8400-e29b-41d4-a716-446655440000
    TransferExten: call_miss_piggy
    TransferContext: default
| Fozzie decides he's tired of telling Kermit jokes and blind transfers him off to Miss Piggy via the dialplan extension `call_miss_piggy`. The fact that a transfer is occurring starts off with the Transfer event. This tells the user who initiates the transfer, who is being transferred, and where the transfer target is going.
    Event: BridgeLeave
    Bridgetype: core
    BridgeUniqueid: 1234
    Channel: SIP/kermit-00000001
    ...
| Kermit leaves the bridge with Fozzie.
At this point, the order of the events that affect Fozzie versus Kermit are not defined. Fozzie and Kermit are no longer bridged together, and their respective events may arrive in any order.
    Event: BridgeLeave
    Bridgetype: core
    BridgeUniqueid: 1234
    Channel: SIP/fozzie-00000002
    ...

    Event: BridgeDestroy
    Bridgetype: core
    BridgeUniqueid: 1234
    ...
| Because Fozzie isn't talking to anyone anymore, he leaves the bridge as well. At this point Asterisk could hang up Fozzie's channel, or, if configured, he could continue on in the dialplan (say, perhaps, to talk to his rubber chicken).
    Event: Newchannel
    Channel: SIP/miss_piggy-00000003
    Uniqueid: 550e8400-e29b-41d4-a716-446655440002
    ...
    Event: DialBegin
    Channel: SIP/miss_piggy-00000003
    Uniqueid: 550e8400-e29b-41d4-a716-446655440002
    ...
    Event: DialEnd
    Channel: SIP/miss_piggy-00000003
    Uniqueid: 550e8400-e29b-41d4-a716-446655440002
    DialStatus: ANSWER
    ...
| The act of Kermit entering into extension `call_miss_piggy` causes a new channel to be created between Asterisk and Miss Piggy. Asterisk immediately dials Miss Piggy, who answers.
    Event: BridgeCreate
    Bridgetype: core
    BridgeUniqueid: 1235
    ...
    Event: BridgeEnter
    Bridgetype: core
    BridgeUniqueid: 1235
    Channel: SIP/kermit-00000001
    Uniqueid: 550e8400-e29b-41d4-a716-446655440000
    ...
| Kermit enters into a bridge. Note that the BridgeUniqueid is different than the previous bridge's BridgeUniqueid.
    Event: BridgeEnter
    Bridgetype: core
    BridgeUniqueid: 1235
    Channel: SIP/miss_piggy-00000003
    Uniqueid: 550e8400-e29b-41d4-a716-446655440002
    ...
| Miss Piggy enters the bridge. At this point, Kermit and Miss Piggy can converse, and the blind transfer is complete.

### 4.5.7. Local Channels

Local channels are different than 'normal' channels in Asterisk, in that they have several properties that make them unique:

- A Local channel never has a physical device that it directly communicates with - it exists as a virtual channel within Asterisk.
- A Local channel can communicate with one or more channels, or directly with an Asterisk application.
- Local channels can be optimized out of a communication path, causing the state of bridges and channels to change.
- A Local channel is actually always two separate channels with a special bridge between them.

While the Local channel exists as a single concept from the perspective of the dialplan, from the perspective of an AMI client, it is always two channels that are tied together by a special bridge. When the bridge between the Local channel halves is formed, a LocalBridge event is raised denoting that the two are connected.

#### 4.5.7.1. Local Channel Creation

When a Local channel is created, a Newchannel event is created for each half of the Local channel being created. Each Local channel half has its own Channel field name and its own Uniqueid - for the purposes of an AMI client, they are two separate channels that can be manipulated separately but whose lifetime is tied together. When either Local channel half is hungup, denoted by a Hangup event, the other Local channel half will also be hungup automatically.

#### 4.5.7.2. Local Channel Bridging

Local channels receive bridge events in the same fashion as other channels. Thus, when they join a bridge, they receive a BridgeEnter event and when they leave a bridge, a corresponding BridgeLeave event. The exception to this is a Local channel bridge, denoted by a LocalBridge event. Once a LocalBridge event occurs, the two Local channel halves can pass frames back and forth between each other. Because the lifetime of the Local channel halves is the same, there is no event representing a Local channel bridge being broken.

Example - Local Channel between two SIP Channels

    Event: Newchannel
    Channel: SIP/miss_piggy-00000003
    Uniqueid: 550e8400-e29b-41d4-a716-446655440002
    ...
| Miss Piggy decides to call Kermit the Frog, and a channel is created between Asterisk and Miss Piggy's SIP device.
    Event: Newchannel
    Channel: Local/kermit@default-00000001;1
    Uniqueid: 550e8400-e29b-41d4-a716-446655440003
    ...
    Event: Newchannel
    Channel: Local/kermit@default-00000001;2
    Uniqueid: 550e8400-e29b-41d4-a716-446655440004
    ...
    Event: LocalBridge
    Channel1: Local/kermit@default-00000001;1
    Channel2: Local/kermit@default-00000001;2
    Uniqueid1: 550e8400-e29b-41d4-a716-446655440003
    Uniqueid2: 550e8400-e29b-41d4-a716-446655440004
    LocalOptimization: No
    ...Event: DialBegin
    Channel: Local/kermit@default-00000001;1
    Uniqueid: 550e8400-e29b-41d4-a716-446655440003
    ...
| Instead of dialing Kermit the Frog directly, a Local channel is created inside Asterisk and Asterisk dials one half of the Local channel. Note that both halves of the Local channel are created first; the Local channel bridges its two halves together; then a DialBegin event indicates that Asterisk is attempting to connect to one half of the Local channel, `Local/kermit@default-00000001;1`.
    Event: DialEnd
    Channel: Local/kermit@default-00000001;1
    Uniqueid: 550e8400-e29b-41d4-a716-446655440003
    DialStatus: ANSWER
    ...
    Event: BridgeCreate
    Bridgetype: core
    BridgeUniqueid: 1234
    ...
    Event: BridgeEnter
    Bridgetype: core
    BridgeUniqueid: 1234
    Channel: SIP/miss_piggy-00000003
    Uniqueid: 550e8400-e29b-41d4-a716-446655440002
    ...
    Event: BridgeEnter
    Bridgetype: core
    BridgeUniqueid: 1234
    Channel: Local/kermit@default-00000001;1
    Uniqueid: 550e8400-e29b-41d4-a716-446655440003
    ...
| The dial operation succeeds and Miss Piggy is bridged with one half of the Local channel that will eventually connect her to Kermit. Note that Miss Piggy doesn't realize that any changes have occurred - from her perspective, nothing has really happened, as the Local channel is a virtual channel and we haven't yet dialed Kermit.
    Event: Newchannel
    Channel: SIP/kermit-00000002
    Uniqueid: 550e8400-e29b-41d4-a716-446655440005
    ...
    Event: DialBegin
    Channel: SIP/kermit-00000002
    Uniqueid: 550e8400-e29b-41d4-a716-446655440005
    ...
    Event: DialEnd
    Channel: SIP/kermit-00000002
    Uniqueid: 550e8400-e29b-41d4-a716-446655440005
    DialStatus: ANSWER
    ...
    Event: BridgeCreate
    Bridgetype: core
    BridgeUniqueid: 5678
    ...
    Event: BridgeEnter
    Bridgetype: core
    BridgeUniqueid: 5678
    Channel: Local/kermit@default-00000001;2
    Uniqueid: 550e8400-e29b-41d4-a716-446655440004
    ...
    Event: BridgeEnter
    Bridgetype: core
    BridgeUniqueid: 5678
    Channel: SIP/kermit-00000002
    Uniqueid: 550e8400-e29b-41d4-a716-446655440005
    ...
| We dial Kermit, and he foolishly answers. He is now bridged with the second half of the Local channel, `Local/kermit@default-00000001;2`, as both that channel and the SIP channel communicating with his SIP device have corresponding BridgeEnter events. In those situations where both a Local channel half and a SIP channel are bridged, there is no ordering guaranteed on which channel enters the bridge first - however, both a Local channel half and the SIP channel will be bridged in the same bridge.
    Event: BridgeLeave
    Bridgetype: core
    BridgeUniqueid: 1234
    Channel: SIP/miss_piggy-00000003
    Uniqueid: 550e8400-e29b-41d4-a716-446655440002
    ...
    Event: Hangup
    Channel: SIP/miss_piggy-00000003
    Uniqueid: 550e8400-e29b-41d4-a716-446655440002
    ...
    Event: BridgeLeave
    Bridgetype: core
    BridgeUniqueid: 1234
    Channel: Local/kermit@default-00000001;1
    Uniqueid: 550e8400-e29b-41d4-a716-446655440003
    ...
    Event: Hangup
    Channel: Local/kermit@default-00000001;1
    Uniqueid: 550e8400-e29b-41d4-a716-446655440003
    ...
    Event: BridgeDestroy
    Bridgetype: core
    BridgeUniqueid: 1234
    ...
    Event: BridgeLeave
    Bridgetype: core
    BridgeUniqueid: 5678
    Channel: Local/kermit@default-00000001;2
    Uniqueid: 550e8400-e29b-41d4-a716-446655440004
    ...
    Event: Hangup
    Channel: Local/kermit@default-00000001;2
    Uniqueid: 550e8400-e29b-41d4-a716-446655440004
    ...
    Event: BridgeLeave
    Bridgetype: core
    BridgeUniqueid: 5678
    Channel: SIP/kermit-00000002
    Uniqueid: 550e8400-e29b-41d4-a716-446655440005
    ...
    Event: Hangup
    Channel: SIP/kermit-00000002
    Uniqueid: 550e8400-e29b-41d4-a716-446655440005
    ...

    Event: BridgeDestroy
    Bridgetype: core
    BridgeUniqueid: 5678
| Miss Piggy, in a fit of frustrated porkine anger, karate chops her SIP phone, causing it to hangup. She leaves the bridge with the Local channel half, `Local/kermit@default-00000001;1`. This causes it to be hungup, as no one else is in the bridge. Because `Local/kermit@default-00000001;1` is hungup, its corresponding other Local channel half, `Local/kermit@default-00000001;2`, leaves the bridge with Kermit's SIP phone and is also hung up. Kermit's SIP channel realizes it's all by itself (it's not easy being green), leaves the bridge it had with its Local channel half, and hangs up as well.

#### 4.5.7.3. Local Channel Optimization

Local channels have an option wherein they can be optimized away if there are two other channels in the Answered state on either end of the Local channel half. This option is performed on Local channel creation, and is communicated back to the AMI clients in the LocalBridge event in the LocalOptimization field. When a Local channel optimization occurs, a LocalOptimization event is sent that indicates the channels involved in the optimization and any bridges they happen to be in. If, after the Local channel optimization, either bridges contains only a single channel, then a single channel in that bridge is moved to the bridge that had the other channel half.

It is not defined which channel is moved first - in this situation, that is an implementation detail left up to Asterisk. Suffice to say, if a Local channel is optimized away, Asterisk attempts to rebridge the channels left over.

Example - Optimizing Local Channel between two SIP Channels

    Event: Newchannel
    Channel: SIP/gonzo-00000001
    Uniqueid: 550e8400-e29b-41d4-a716-446655440000
    ...
| Gonzo decides to call Kermit the Frog, and a channel is created between Asterisk and Gonzo's SIP device.
    Event: Newchannel
    Channel: Local/kermit@default-00000001;1
    Uniqueid: 550e8400-e29b-41d4-a716-446655440001
    ...
    Event: Newchannel
    Channel: Local/kermit@default-00000001;2
    Uniqueid: 550e8400-e29b-41d4-a716-446655440002
    ...
    Event: DialBegin
    Channel: Local/kermit@default-00000001;1
    Uniqueid: 550e8400-e29b-41d4-a716-446655440001
    ...
| Instead of dialing Kermit the Frog directly, a Local channel is created inside Asterisk and Asterisk dials it.
    Event: DialEnd
    Channel: Local/kermit@default-00000001;1
    Uniqueid: 550e8400-e29b-41d4-a716-446655440001
    DialStatus: ANSWER
    ...
    Event: BridgeCreate
    Bridgetype: core
    BridgeUniqueid: 1234
    ...
    Event: BridgeEnter
    Bridgetype: core
    BridgeUniqueid: 1234
    Channel: SIP/gonzo-00000001
    Uniqueid: 550e8400-e29b-41d4-a716-446655440000
    ...
    Event: BridgeEnter
    Bridgetype: core
    BridgeUniqueid: 1234
    Channel: Local/kermit@default-00000001;1
    Uniqueid: 550e8400-e29b-41d4-a716-446655440001
    ...
    Event: LocalBridge
    Channel1: Local/kermit@default-00000001;1
    Channel2: Local/kermit@default-00000001;2
    Uniqueid1: 550e8400-e29b-41d4-a716-446655440001
    Uniqueid2: 550e8400-e29b-41d4-a716-446655440002
    LocalOptimization: Yes
    ...
| The dial operation succeeds and Gonzo is bridged with one half of the Local channel that will eventually connect him (it?) to Kermit. The Local channel itself has also decided to go ahead and bridge the two local halves together, since we have one half of the full chain of channels established. Note that we are told at this point that the Local channel will attempt to optimize itself away, if Kermit answers.
    Event: DialBegin
    Channel: SIP/kermit-00000002
    Uniqueid: 550e8400-e29b-41d4-a716-446655440003
    ...
    Event: DialEnd
    Channel: SIP/kermit-00000002
    Uniqueid: 550e8400-e29b-41d4-a716-446655440003
    DialStatus: ANSWER
    ...
    Event: BridgeCreate
    Bridgetype: core
    BridgeUniqueid: 5678
    ...
    Event: BridgeEnter
    Bridgetype: core
    BridgeUniqueid: 5678
    Channel: Local/kermit@default-00000001;2
    Uniqueid: 550e8400-e29b-41d4-a716-446655440002
    ...
    Event: BridgeEnter
    Bridgetype: core
    BridgeUniqueid: 5678
    Channel: SIP/kermit-00000002
    Uniqueid: 550e8400-e29b-41d4-a716-446655440003
    ...
| We dial Kermit and he answers. He is now bridged with the second half of the Local channel, `Local/kermit@default-00000001;2`. Note that even in the optimizing case, both the Local channel halves and the other channels involved first enter their respective bridges.
    Event: LocalOptimization
    Channel1: Local/kermit@default-00000001;1
    Uniqueid1: 550e8400-e29b-41d4-a716-446655440001
    BridgeUniqueid1: 1234
    Channel2: Local/kermit@default-00000001;2
    Uniqueid2: 550e8400-e29b-41d4-a716-446655440002
    BridgeUniqueid2: 5678
    ...
    Event: BridgeLeave
    Bridgetype: core
    BridgeUniqueid: 5678
    Channel: SIP/kermit-00000002
    Uniqueid: 550e8400-e29b-41d4-a716-446655440003
    ...Event: BridgeEnter
    Bridgetype: core
    BridgeUniqueid: 1234
    Channel: SIP/kermit-00000002
    Uniqueid: 550e8400-e29b-41d4-a716-446655440003
    ...
| Asterisk determines that it can optimize away the Local channel. It notifies the AMI client that this is about to occur, which Local channels are involved, and what bridges they are currently in. It starts first by moving Kermit into Gonzo's bridge. From their perspective, nothing has happened - they just now happen to be in the same bridge, instead of having a Local channel pass frames for them. Note that before this happens, a LocalOptimization event is sent indicating that some shenanigans are about to ensue with the Local channels and by extension, the bridges they are in.
    Event: BridgeLeave
    Bridgetype: core
    BridgeUniqueid: 5678
    Channel1: Local/kermit@default-00000001;2
    Uniqueid1: 550e8400-e29b-41d4-a716-446655440002
    ...
    Event: BridgeLeave
    Bridgetype: core
    BridgeUniqueid: 1234
    Channel1: Local/kermit@default-00000001;1
    Uniqueid1: 550e8400-e29b-41d4-a716-446655440001
    ...
    Event: Hangup
    Channel1: Local/kermit@default-00000001;1
    Uniqueid1: 550e8400-e29b-41d4-a716-446655440001
    ...
    Event: Hangup
    Channel1: Local/kermit@default-00000001;2
    Uniqueid1: 550e8400-e29b-41d4-a716-446655440002
    ...Event: BridgeDestroy
    Bridgetype: core
    BridgeUniqueid: 5678
    ...
| The Local channels now leave their bridges and are hung up. As a result, the bridge with no channels left in it - Bridge 5678 - is destroyed.

### 4.5.8. Masquerades

Masquerades have changed

In the past, masquerades occurred rather frequently - most often in any scenario where a transfer occurred or where a `pbx_thread` needed to be associated with a channel. This has now changed. Masquerades now rarely occur, and are never communicated to AMI clients. From the perspective of AMI clients, nothing changes - you still use your handle to a channel to communicate with it, regardless of the presence (or lack thereof) of a masquerade operation.

This note only exists to explicitly call out that fact.

## 4.6. Transports

AMI supports the following transport mechanisms:

- TCP/TLS
- HTTP/HTTPS

When clients connect over HTTP/HTTPS, AMI events are queued up for retrieval. Events queued up for a client are automatically retrieved and sent in the response to any POST operation. The WaitEvent action can be used to wait for and retrieve AMI events.

# 5. Security Considerations

AMI supports security at the transport level via TLS using OpenSSL.

## 5.1. Class Authorizations

Do not rely on class authorizations for security. While they provide a means to restrict a client's access to sets of functionality, there are often ways of achieving similar functionality through multiple mechanisms. Do NOT assume that because a class authorization has not been granted to a client, that they can't find a way around it. In general, view class authorizations as a coarse grained way of providing sets of filters.

Events and actions are automatically classified with particular class authorizations. Clients can be configured to support some set of class authorizations, filtering the actions that they can perform and events that they receive. The supported class authorizations are listed below.

Class Type | Description
--- | ---
system | The item is associated with something that reports on the status of the system or manipulates the system in some fashion
call | The item is associated with calls, i.e., state changes in a call, etc.
log | The item is associated with the logging subsystem
verbose | The item is associated with verbose messages
command | The item is associated with execution of CLI commands through AMI
agent | The item is associated with Queue Agent manipulation
user | The item is associated with user defined events
config | The item is associated with manipulating the configuration of Asterisk
dtmf | The item is associated with DTMF manipulation
reporting | The item is associated with querying information about the state of the Asterisk system
cdr | The item is associated with CDR manipulation
dialplan | The item is associated with dialplan execution
originate | The item is associated with originating a channel
agi | The item is associated with AGI execution
cc | The item is associated with call completion
aoc | The item is associated with Advice of Charge
test | The item is associated with some test action
message | The item is associated with out of call messaging
all | The item has all class authorizations associated with it
none | The item has no class authorization associated with it

## 5.2. Access Control Lists

Access Control Lists can be used to filter connections based on address. If an attempt to connect from an unauthorized address is detected, the connection attempt will be rejected.

## 5.3. Authorization

Authorization can be provided via the Login action. If a client fails to provide a valid username/password, the connection attempt and any subsequent actions will be rejected. Events will not be sent until the client provides authorized credentials.

The actions that are excluded from successful login are:

- Login
- Logout
- Challenge

The action Logoff has been replaced by a corresponding action Logout. Logoff has been deprecated in favor of Logout.

# 6. AMI Configuration

AMI supports the following configuration options. Note that additional configurations MAY be specified; however, these configuration options are valid for Asterisk 12.

## 6.1. General Settings

Option | Type | Description | Default
--- | --- | --- | ---
enabled | Boolean | Enable AMI | no
webenabled | Boolean | Enable AMI over HTTP/HTTPS | no
port | Integer | The port AMI's TCP server will bind to | 5038
bindaddr | IP Address | The address AMI's TCP server will bind to | 0.0.0.0
tlsenable | Boolean | Enable TLS over TCP | no
tlsbindaddr | IP Address | The address AMI's TCP/TLS server will bind to | 0.0.0.0:5039
tlscertfile | String | The full path to the TLS certificate to use | /tmp/asterisk.pem
tlsprivatekey | String | The full path to the private key. If no path is specified, tlscertfile will be used for the private key. | /tmp/private.pem
tlscipher | String | The string specifying which SSL ciphers to use. Valid SSL ciphers can be found at http://www.openssl.org/docs/apps/ciphers.html#CIPHER_STRINGS |
allowmultiplelogin | Boolean | Allow multiple logins for the same user. If set to no, multiple logins from the same user will be rejected. | Yes
timestampevents | Boolean | Add a Unix epoch Timestamp field to all AMI events | No
authlimit | Integer | The number of unauthenticated clients that can be connected at any time |

## 6.2. Client Settings

Note that the name of the client settings context is the username for the client connection.

Option | Type | Description | Default
--- | --- | --- | ---
secret | String | The password that must be provided by the client via the Login action |
deny | ACL | An address/mask to deny in an ACL. This option may be present multiple times. |
permit | ACL | An address/mask to allow in an ACL. This option may be present multiple times. |
acl | String | A Named ACL to apply to the client. |
setvar | String | A channel variable key/value pair (using the nomenclature VARIABLE=value) that will be set on all channels originated from this client |
eventfilter | Regular Expression | This option may be present multiple times. This options allows clients to whitelist or blacklist events. A filter is assumed to be a whitelist unless preceeded by a '!'. Evaluation of the filters is as follows: If no filters are configured all events are reported as normal. If there are white filters only: implied black all filter processed first, then white filters. If there are black filters only: implied white all filter processed first, then black filters. If there are both white and black filters: implied black all filter processed first, then white filters, and lastly black filters. |
read | String | A comma delineated list of the allowed class authorizations applied to events | all
write | String | A comma delineated list of the allowed class authorizations applied to actions | all
tag | String | If present, the client will only receive events that are related to channels created in relation to endpoints that are configured with the same tag. See Publish/Subscribe for more information. |

## Attachments:

AMI Local Channels (application/gliffy+xml)
AMI High Level Diagram (application/gliffy+xml)
AMI High Level Diagram.png (image/png)
AMI Local Channels Diagram (application/gliffy+xml)
AMI Local Channels Diagram.png (image/png)
AMI Local Channels.png (image/png)