[asterisk-users] Channel names with semicolons

[Thomas Ray]

From: asterisk-users <asterisk-users-bounces at lists.digium.com> on behalf of "Joshua C. Colp" <jcolp at sangoma.com>
Reply-To: Asterisk Users Mailing List - Non-Commercial Discussion <asterisk-users at lists.digium.com>
Date: Wednesday, September 7, 2022 at 10:23 AM
To: Asterisk Users Mailing List - Non-Commercial Discussion <asterisk-users at lists.digium.com>
Subject: Re: [asterisk-users] Channel names with semicolons

 

On Wed, Sep 7, 2022 at 11:17 AM Antony Stone <Antony.Stone at asterisk.open.source.it> wrote:

On Wednesday 07 September 2022 at 11:44:54, Antony Stone wrote:

> Hi.

This is a follow-up to an email I posted earlier today to the list, although I 
haven't seen it come back yet.  If it's under moderation for some reason, I 
hope some kindly admin will release it :)

 

There's nothing in the moderator queue that I can see.

 


> I'm trying to deal with a problem regarding putting a call on hold and then
> later resuming it.  I am using chan_sip throughout, and Asterisk 16.

<snip detail from previous email>

> The main thing which is puzzling me about this is that I see examples of
> both Local/number at context-00000ce9;1 and Local/number at context-00000ce9;2
> during the processing of the calls.
> 
> What is the significance of the number following the semi-colon?
> 
> I also see in verbose logging output:
> 
> [2022-09-07 09:37:57.310706] pbx VERBOSE[29148]: dial.c:598 in
> handle_frame: Local/number at context-00000ce9;1 answered
> 
> [2022-09-07 09:37:57.310792] pbx VERBOSE[29155][C-00001265]:
> bridge_channel.c:2252 in bridge_channel_internal_push_full: Channel
> SIP/Trunkname-00002b55 joined 'simple_bridge' basic-bridge <7e260e93-
> abd4-48ea-96f1-33601165dba2>
> 
> [2022-09-07 09:37:57.310937] pbx VERBOSE[29149][C-00001265]:
> bridge_channel.c:2252 in bridge_channel_internal_push_full: Channel
> Local/number at context-00000ce9;2 joined 'simple_bridge' basic-bridge
> <7e260e93- abd4-48ea-96f1-33601165dba2>
> 
> 
> So, when the channel Local/number at context-00000ce9;1 gets answered, the
> result is to bridge the channels Local/number at context-00000ce9;2 and
> SIP/Trunkname-00002b55

I see something very similar in the documentation about local channels at 
https://wiki.asterisk.org/wiki/display/AST/Using+Callfiles+and+Local+Channels - 
there are examples of both devices-ecf0;1 and devices-ecf0;2 but no mention of 
what the final digit means.

Can anyone enlighten me please?

 

A single channel can't do two things at once (you can't have a channel talking to Alice while also executing the Voicemail dialplan application for example) - so Local channels solve this by having 

two independent channels that exchange things back and forth internally. The ;2 leg is the one that gets sent into the dialplan, while the ;1 leg is doing whatever dialed it decides to do with it. If you send audio to ;1 it then pops out of ;2, and vice versa.

 

--- 

Oh I had the channel numbers reversed in my previous example. So yeah, this.

 

 

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