Behavior of outgoing calls through a sip trunk from a shared line

[gurumbha]

Hi Team,

I would like to understand the behavior of outgoing calls through a SIP Trunk when "Run On All Active Unified CM Nodes" is enabled in both Trunk configuration and Route List. 
Specifically when the outgoing calls are done from shared lines in different phones which are registered in different CUCM Subscribers.
In 8.6, calls always go through the CUCM Subscriber where the first created phone (sharing line) is registered to.
Please can anyone give me the explanation for this? Is there any document which may explain?

Thanks,

Guru

[Chris Deren]

Guru,

It will go through the Sub that the phone is registered to, so nothing unique about shared line here. This is described in SRND under the SIP trunk section.

Chris

[Ayodeji Okanlawon]

+5 to Chris..

Just to add to what Chris said, I wrote a blog a while back specifically on this. Here is a snapshot that answers your question: NB: Lines are irrelevant, it is the phones that determines which node the call will originate from

When the "Run on all active CM Node" is selected on the RL and on the SIP Trunk the Route Local feature uses this algoritm to determine which node the call will orginate from;

• Use the node that the inbound call arrived on. e.g CUCM server IP Phone is registered to.

Please refer to the blog here for detailed explanation of how things work with regards to the "run on all active cucm node feature"

https://supportforums.cisco.com/blog/12088366/sip-trunks-and-run-all-active-cm-nodes

[gurumbha]

Thanks a lot for the quick reply :)

I understand 

In addition to the above notes, may i know why the call always goes through the first phone (subscriber in the cluster) which is registered to cucm only and not the other subscriber say second?

Please reply...

Thanks,

Guru

[Chris Deren]

Correct.

[gurumbha]

Thanks for the inputs. The concepts are clear to me. But this is not my question. Let me explain with a scenario.

This is the scenario (topology):

• Two deskphones, both with same line. This is both sharing a single Directory Number in the CUCM.
• They are registered to different nodes in the cluster.
• Both SIP Trunk and Route List/Route Group are configured with "Run on all Active Unified CM Nodes" enable.

Looking at the deskphone that was created SECONDLY (on the CUCM), no matter what cluster node it is registered to, all outbound calls through the SIP Trunk are made from the node where the FIRST created deskphone is registered to.

You can change that SECOND created deskphone to be registered in different cluster nodes, all outbound calls are done from the same cluster node (where the FIRST created deskphone is registered to).

I really want to know why this is happening..

Thanks,

Guru