Asterisk Manager api Originate的妙用

Originate Using Asterisk Local Channels

Whenever you want to place a call between two extensions in the dialplan you have to use Local channels.
The OriginateAction that you use when placing calls through the Manager API requires a channel name for the first leg. Usually your application has no knowledge of the dialplan details, i.e. it does not know which channel is triggered by an extension (maybe it's a SIP hardphone, an IAX device or a link to another Asterisk server). What you want to do is "place a call between number a and number b" and leave the rest to Asterisk.

Local channels act as a proxy to the real channels mapped to an extension. So to place a call from 1310 to 1299 your Originate looks like:

1.Channel: Local/1310@from-local

2.Context: from-local

3.Exten: 1310

4.Priority: 1

1.Channel: SIP/1310

2.Context: from-local

3.Exten: 1299

4.Priority: 1

There is an article about Local Channels at voip-info.org that covers the basics.

So that's all very nice and looks straight forward. It becomes more interesting if you have a look at what happens under the hood:

A Local channel actually consists of two channels in Asterisk: Local/XXX,1 and Local/XXX,2. The Local/XXX,2 channel traverses the dialplan starting at the context and extension you provided. In our example this is the extension 1310 in from-local. If you watch the CLI or the events triggered you will see:

1.Set(_ALERT_INFO=<Bellcore-dr1>)

2.Macro(localexten|1310|SIP/1310)

3.Dial(SIP/1310|30|t)

This corresponds to the defintion of 1310 in my dialplan:

01.[from-local]

02.exten => 1310,1,Set(_ALERT_INFO=<Bellcore-dr1>)

03.exten => 1310,n,Macro(localexten,${EXTEN},SIP/${EXTEN})

04.  

05.[macro-localexten]

06.exten => s,1,Dial(${ARG2},30,t)

07.exten => s,n,Goto(s-${DIALSTATUS},1)

08.exten => s-NOANSWER,1,Voicemail(u${ARG1})

09.exten => s-NOANSWER,n,Hangup

10.exten => s-BUSY,1,Busy

11.exten => _s-.,1,Goto(s-NOANSWER,1)

The Dial command triggers an additional channel (SIP/1310). This is the actual channel that is proxied by the Local channel.

The other side of the Local channel, Local/XXX,1, is used for the desination. In our example this is the extension 1299 in from-local. You see similar events for this channel. The actual channel that is triggered for 1299 is an IAX channel to another Asterisk server: IAX2/iax_reucon_net-3.

Now we reach the point where we have four channels set up: The two sides of the Local channel and the two "real" channels SIP/1310 and IAX2/iax_reucon_net. Two channels are now longer needed and will vanish. Before this happens all data of the proxied channel is copied (masqueraded) to Local/XXX,1 so that Local/XXX,1 is renamed to SIP/1310. The "old" SIP/1310 channel is renamed to SIP/1310-0820f718<MASQ> and finally to Local/1310@from-local-1e71,1<ZOMBIE> before it is hung up. Local/XXX,2 is hung up without any renaming.
So in the end you have exactly what you would have expected: Two channels, SIP/1310 and IAX2/iax_reucon_net up and connected.

I have prepared a nice diagram that shows all these steps in detail and helps you understand what happens:

评论

3 楼 sunflowers 2010-09-20  

renwolang521 写道

我用软电话没有试成功，当执行如上 AMI 命令时，首先分机1310振铃 接起来之后又会再振铃再接起 它把 “Local/xxx,1” 和 “Local/xxx,2”这两个通道连接起来了,软电话用的是X-lite3.0免费版。CLI输出完整如下：

看你输出的日志记录，你使用的应该是asterisk1.6的内核，这个问题也是我最近发现的，
请看我的博文，希望能帮助到你，http://sunflowers.iteye.com/blog/759614

2 楼 sunflowers 2010-09-20  

请看我的博文，可能是这个问题，http://sunflowers.iteye.com/blog/759614

1 楼 renwolang521 2010-09-19  

不知楼主试过这个否？我没试成功，若楼主有空，帮忙看下。
[quote=AMI]
Action: Originate
Channel: Local/1310@from-local
Context: from-local
Exten: 1310
Priority: 1

我用软电话没有试成功，当执行如上 AMI 命令时，首先分机1310振铃 接起来之后又会再振铃再接起 它把 “Local/xxx,1” 和 “Local/xxx,2”这两个通道连接起来了,软电话用的是X-lite3.0免费版。CLI输出完整如下：
[quote=CLI]

    -- Executing [1310@from-local:1] Set("Local/1310@from-local-003c;2", "_ALERT_INFO=<Bellcore-dr1>") in new stack
    -- Executing [1310@from-local:2] Macro("Local/1310@from-local-003c;2", "localexten,1310,SIP/1310") in new stack
    -- Executing [s@macro-localexten:1] Dial("Local/1310@from-local-003c;2", "SIP/1310,30,t") in new stack
  == Using SIP RTP CoS mark 5
    -- Called 1310
    -- SIP/1310-00000002 is ringing
    -- SIP/1310-00000002 is ringing
    -- SIP/1310-00000002 answered Local/1310@from-local-003c;2
    -- Executing [1310@from-local:1] Set("Local/1310@from-local-003c;1", "_ALERT_INFO=<Bellcore-dr1>") in new stack
    -- Executing [1310@from-local:2] Macro("Local/1310@from-local-003c;1", "localexten,1310,SIP/1310") in new stack
    -- Executing [s@macro-localexten:1] Dial("Local/1310@from-local-003c;1", "SIP/1310,30,t") in new stack
  == Using SIP RTP CoS mark 5
    -- Called 1310
    -- Local/1310@from-local-003c;1 requested special control 20, passing it to SIP/1310-00000003
  == Spawn extension (macro-localexten, s, 1) exited non-zero on 'Local/1310@from-local-003c;2' in macro 'localexten'
  == Spawn extension (from-local, 1310, 2) exited non-zero on 'Local/1310@from-local-003c;2'
    -- SIP/1310-00000003 is ringing
    -- SIP/1310-00000003 is ringing
    -- SIP/1310-00000002 requested special control 16, passing it to SIP/1310-00000003
    -- Music class default requested but no musiconhold loaded.
    -- SIP/1310-00000002 requested special control 20, passing it to SIP/1310-00000003
    -- SIP/1310-00000003 answered SIP/1310-00000002
  == Spawn extension (macro-localexten, s, 1) exited non-zero on 'SIP/1310-00000002' in macro 'localexten'
  == Spawn extension (from-local, 1310, 2) exited non-zero on 'SIP/1310-00000002'