UC500 as Key System with SIP Trunk?

Unanswered Question
Jul 4th, 2010

I have a customer who wants to be able to press a button on their phone and automatically access a phone line, just like their old Key System behaved.  I've tried to convince them that PBX mode offers more flexibility, but it's not happening, so no need to discuss that.

I am integrating AT&T's IP Flex circuit into the system.  Is it possible to run the UC540 in Key System mode with the IP Flex trunk?  Is there another way to accomplish this in PBX mode?

Please let me know ASAP.



I have this problem too.
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David Harper Sun, 07/04/2010 - 19:12

This is something that comes up periodically, and whether you can do it easily depends a little whether you are using CCA or CLI to configure the system.  Essentially the wya this is done is as follows:

  1. Create a collection of shared lines equal in number to the number of calls supported on the SIP trunk.  So if the trunk (or the underlying WAN bandwidth) supports four simultaneous calls, then you need four shared lines.
  2. Configure the first shared line to be the target of calls incoming from the SIP trunk, and then link the shared lines using call forward busy so that an incoming call will roll from the first line to the second, then to the third and so on until it finds an available line to ring on.
  3. Configure the dialplan so that calls outbound from those shared lines do not require an access code to be dialed.
  4. Assign the shread lines to buttons on the phones in the same way you would assign trunk lines if you were using analog lines.
  5. Typically you would also assign the first button on the phone to be a dialable intercom for internal calls.

This is relatively straight forward using CLI for configuration, but unfortunately, cannot be done completely using CCA yet.  Specifically, step 3 is not yet supported in CCA, and neither is step 5.  Support for dialable intercom (step 5) should be available very soon, but step 3 will remain a gap for a little while yet.  If you follow the OOB configuration guidelines, you should be able to set almost all of this up using CCA, and then assign an inbound translation pattern on the shared lines that prefixes an access code onto the dialed number of calls placed on the phone which would address step 3.  That would keep the non-CCA configuration to a minimum.



stacy.thompson Tue, 07/06/2010 - 15:10


     Do you first select key system mode in CCA? or are you talking about how to do this with CCA being set as IP PBX system?


David Harper Tue, 07/06/2010 - 16:05

No, this assumes PBX mode.

Actually, since we enabled support for CO Lines in PBX mode, I tend to see Keysystem mode as something of a legacy setting that has little use now.  We really need to revamp this into being more like a set of template starting configs, rather than an explicit PBX or Keysystem mode.  But that is a job for a little further down the track I think.  There are a few more important changes to CCA we need to make first.



Damian Halloran Fri, 11/04/2011 - 01:02


This is an old thread but a client is very keen for outbound SIP calls to show under a button on each handset.

To understand step 3 is this done so that when the user doesn't dial an access code the system will immediately select one of the shared lines for the outbound call, and then the call will show as being on one of these shared lines on everyones handset?

BTW thanks for the presentation in Melbourne last week - the upcoming looks excellent especially the smart phone voice clients.


David Harper Fri, 11/04/2011 - 01:10

Sort of.  The idea is that when making an outbound call, you just press an 'available' button to go off hook.  At that point, the button shows up as being in use on all the phones because it is a shared line.  The tweak to avoid the use of the access code is purely to replicate the key system experience.  It is easy enough to do with CLI.  Basically you just create a translation rule that prepends the access code onto the called number of any calls placed on that line.  Unfortunately, this is still not available in CCA, as this requirement nevers seems to be quite as urgent as some of the other things on the ToDo list.  It has always been more of a niche requirement.



Damian Halloran Sat, 11/05/2011 - 19:12

Thanks David - one last question is there any way to make a speed dial button use one of the shared lines to dialout?



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