CUBE - New Deployment Issue - Cancel local RBT

[StewieGriffin]

Hello,

Scheme:

Cisco SCCP-based IP Phone > CUCM 9.1 w/ SIP Trunk > CUBE (28XX, 151-4.M7) > SIP ITSP

CUCM Active Call Proc. Node IP: 10.10.10.9
CUBE Inside Interface IP: 10.10.10.10
CUBE Outside Interface IP: 20.20.20.20
ITSP SBC IP: 30.30.30.30
ITSP SIP domain: itsp.domain
Calling Pty: 9017654321 (translated in CUCM's route pattern which addresses CUBE)
Called Pty: 9011234567

Symptom:

While doing outbound call calling party (IP Phone) hears ring back tone probably generated by CUCM.
It happens every time even if PSTN/GSM number is switched off and some informational announcement is generated from far-end.

Thoughts:

Seems response 183 w/ SDP is carried normally from ITSP towards CUCM.
CUBE by default do bidirectional path upon receipt 183 w/ SDP.
http://www.cisco.com/c/en/us/td/docs/ios/voice/command/reference/vr_book/vr_r1.html#wp1571385

Question:

How to make calling party to hear voice path announcements in the forward direction before the call is connected?

[Suresh Subramanian · Accepted solution]

can you try enabling Early Offer in the SIP Profile (Non Standard SIP Profile - CUBE) you've applied to Trunk by checking 'Early Offer Support For Voice & Video Call (insert MTP if needed)'?

if that doesn't help, you can enable PRACK on the same SIP Profile and see if it works?

you can refer this link for your guidance.

http://www.cisco.com/c/en/us/support/docs/voice/session-initiation-protocol-sip/116086-configure-cube-cucm-sip-00.html

[StewieGriffin]

Suresh,

Both recommendations are workable, thank you.

I've chosen the second one (enabling PRACK if 1xx contains SDP on CUCM side (SIP Trunk's SIP Profile) because it doesn't require additional MTP resources.

Also this good URL was helpfull

http://www.ucguerrilla.com/2014/02/dealing-with-provisional-response-and.html

[Suresh Subramanian]

but there is no harm in enabling the Early Offer in the SIP profile because this new feature introduced in CUCM 8.x to avoid enabling MTP for all calls. CUCM will insert MTP only if needed. when enabling that EO in SIP Profile, the Cisco Phone's IP address & CODEC capabilities are sent in the SDP. I'd say you can still enable EO on the profile.