CUCM T1/E1 Hairpin

[mcgeehonjp]

I have a problem where I answer an inbound call on my E1 PRI and then transfer the call off-net over the same E1 PRI. It seems that CUCM does not fully release the call and two channels are used for this inbound / outbound transfer. Is there something I am missing on CUCM or on the E1 interface to allow or force off-net transfers to release and not hairpin or tie up channels?

I am running CUCM 10.5.2 with MGCP control of my voice gateway.

Thanks

[Jaime Valencia]

Does your telco support TBCT?

[RAustin70]

Hey Jaime, I have been searching the forums for an answer to a question similar to this one, and I see you comment a lot on the posts, I was hoping I could ride on this thread instead of starting up a new basically duplicate thread.

With this Pandemic hitting, 90% of our workforce is teleworking.  They want to forward their deskphones to a home phone.  We run CUCM 11.5SU6 behind MGCP controlled T1 lines on our ISR 4431's.  Is there a way to prevent hairpinning/tromboning calls that come in, hit CFWA and go back out the T1?  You mentioned Telco support of TBCT here, and in another thread I think you mentioned you need H323 for TBCT, which we don't use.

Right now we are denying the forwarding as we only have 6 T1's for ~2,000 end users.  If we can find a way to break off the calls if CUCM doesn't have to control them I'd be a happy camper

Rob

[Jaime Valencia]

No, you can't do anything about this with MGCP.

Your telco needs to support TBCT, if they don't, no way to do this.

And that's a TCL script which doesn't work with MGCP.

[RAustin70]

Thanks Man, you are always on top of things in the UC Community.  I really appreciate that.

Rob

[Mohammed al Baqari]

This is how it works in CUCM (unlike call forward). CUCM will accept call
one, establish call two then hairpin the call legs on the voice gateway.
This is important for call billing (caller#1 pays for first call and
transferor pays for second call).