Understanding The Right Way To Get Started With Multiple Trunks/extensions

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Background: I dabbled with asterisk years ago, and more recently have more-or-less functioning IncrediblePBX systems for experimenting, but I want to understand more so I’m now working with distro packages
(Ubuntu) and hand edited configurations files.

I have three SIP “trunks”, each providing me with a UK telephone number. They are for my home (1), my wife’s home-based bookkeeping business (2), and for taking support calls on from work (3). For
“handsets” I only really have mobile phones running SIP/IAX clients, although I might put a “real” desktop handset on my wife’s desk at some point.

The objective is that my wife picks up calls to (1) or (2), I pick up calls to (2) or (3), and maybe a colleague might also pick up calls to

I can see how to do this with call groups, but I would like to be able to see at the handset which trunk the call has come in on, which I
don’t think I can do that way?

Or I could just set up multiple connections in the SIP/IAX client, so each trunk has its own extension and we each connect to multiple extensions as required. That has the added advantage of making the voicemail relate to which trunk the call comes in on, which is also more appropriate here.

However, the latter option “feels” wrong somehow and I haven’t found any examples suggesting it’s the right way to do things.

Also, I am keen to minimise battery overhead on the mobile phones – is linking to multiple accounts is less efficient?

PS: Although I only really care about inbound calls at the moment, I
daresay I will want to handle internal calls at some point too, although nothing stops me having dedicated per-user extensions as well as per incoming trunk.


2 thoughts on - Understanding The Right Way To Get Started With Multiple Trunks/extensions

  • For some reason I didn’t see David’s reply by email, and have copy/pasted the following from the list archives to make my reply, sorry if that messes up anyone’s threading.

    I’m trying to avoid a GUI for now so that I learn something, but knowing how to do it that way is appreciated, thanks.

    I haven’t got my head round the syntax yet; will this retain the real caller ID but add something to it, or will I lose the real ID?

    From your answers I take it that it is “better” if all users have their own extension and I route calls to the relevant extensions as required, rather than having users monitor multiple extensions. It’s what I expected but can I ask why? Is it a scalability or performance issue, do I lose something by not doing it this way, or is it just about doing things “right”?

    With the above, what’s the best way to handle voicemail? I would expect anyone who could have taken the call to be able to access the voicemail, and once one person has “dealt with” a message it’s no longer a new message to anyone else.


  • In the ‘home-number’ example that was provided the caller ID was being replaced with the string ‘Home’

    It’s easy to prepend the caller ID instead however.


    You could even get fancy and set it based on what number was called, This would prepend the CallerID with the last 4 digits of the incoming number assuming that your calls come in to an extension that way:


    There is no ‘Best’ or ‘Better’ way to handle extension and voicemail routing, It’s all down to your preference as a programmer and your users.

    Try things, Find what works best for you, The only thing you have to loose is your free time and if you are like me you will have fun during the process.