Does CUCM has a feature to remember incoming/outgoing SIP trunks?

[trienguy]

Hi All,

We have a network with multiple SIP trunks.

Incoming calls can be load sharing across these trunks.

Outgoing calls we also load sharing across all these trunks (Circular setup)

issue we have:

Mobile calls  in via SIP Trunk A (CityA) --> CUCM --> Cisco Handset ->transfer out -> SIP Trunk B (City B)

Does the CUCM has a feature when you turn it on.. it should remember where the incoming calls via what sip trunk so whenever we send the call

backout it should use the same SIP Trunk?

if the CUCM doesn't have this feature, then we need to reserve lots of bandwidth for the RTP stream from SIP trunk A to SIP Trunk B

Many Thanks,

Trieu

[Terry Cheema]

Not sure if I understand your question completely on what you are trying to achieve but there is no such thing in CUCM that it will remember where the call came from and route the call reverse out on same path.

But it appears to me you are trying to achieve Least Cost Routing LCR/TEHO. You can configure your call routing to make the decisions by using the route patters/Partitions/CSSes etc. You can also use digit manipulation to influence call routing in CUCM.

-Terry

Please rate all helpful posts.

[trienguy]

Terry no I don't want to do least cost routing !! Just imagine if someone calls you on a cisco handset and you want to transfer this call back out  to the pstn if you don't remember the same sip trunk how do hand it off back to the pstn ?? 

If I have 1000 transfer calls  that means I need to reserve 100kx1000 calls across my network ?

Why cisco developer doesn't think of this?? I have raised this issue to cisco tac and they agreed this feature doesn't exist they told me to raise this concern to my account manager !!

[Jaime Valencia]

Probably because the developers cannot think of every single scenario that is out there, this is the first time I've seen someone request this, and I've been working for a good number of years on this. And TAC did exactly what they should, if you want to have something considered for a future release, you need to reach your AM, and submit a PER, this is not something out of the ordinary.

You need to know, that submitting a PER, is by no means guarantee that this will be in a future release.

[Terry Cheema]

Hey mate can you explain your call flow/topology a bit more.

You have got a CUCM with SIP trunks to a Service Provider for PSTN hand off? Whats the topology of the SIP centralised through DCs or distributed? Are the SIP trunks to same provider or to different providers? Are you using any SBC (CUBE/Acme or anything)?

If you can explain a little bit more about your topology I would be able to help you in a better way, even though CUCM has no reverse path look out feature but depending upon the environment you can still find a way around hopefully.

-Terry

[trienguy]

Hi Terry 

you still don't get the call flow?

SIP Trunk A (CityA) --> CUCM --> Cisco Handset ->transfer out -> SIP Trunk B (City B) 

1. 1 single sip trunk can handle all calls from any cities of your country !!!
2. incoming calls handle by Telco ie load sharing with all your sip trunks
3. outgoing calls handle by CUCM with two of your SIP Trunks in this call flow with "Circular" configuration ie 1 single route Group with with two sip trunks

Imagine you have 5 operators with ARC clients they need to handle incoming calls then transfer either internal or external. when you transfer external you will encounter this issue

some calls they can hair pin (ISDN terminology) back out to the telco when they coming in/going out on the same trunk. But if they go out via a different trunk you need to hold this RTP stream until the callers drop off.

[Terry Cheema]

As said before reverse flow is not possible. Operator is making a new call when she is trying to transfer, so there is no way of influencing the call routing here.

"But if they go out via a different trunk you need to hold this RTP stream until the callers drop off"

Why would be that? You are connecting two PSTN phones why would RTP (or anything) be flowing through your network? Anyways I did ask the specifically about SIP topology to try to understand, why would you have this strange requirement?

I am pretty certain as Jaime has mentioned there are not very high chances of getting this enhancement.

To me it still doesn't make sense. But regardless, you have got answer from various places, the feature you are asking is not available and nor is the likelihood of this being introduced in any near future.

-Terry

[trienguy]

I understand all that 

why it doesn't make sense ?? If this was isdn why your iOS can do it?

Why can't the cucm do it ?? If I have 100 calls why do I need to pay bandwidth for these.calls

[Jaime Valencia]

No, there is no such thing in CUCM