Unity Express AA Transfer no Ring-back – Perception is Key!

This one was a very funny one and I’d like to share with you. After an install of a remote office using the following equipment:

CIsco 2901 with an ISM for CUE and an AutoAttendant that when the office is open sends the call to a Hunt Group in CUCM and when they are close the AA (prompts) really kicks in. Nothing too crazy right?

After 1 month of the installation received a call that when someone calls the main number they hear not ring back (only death air) until someone answers the call. After this one I had few things to look at but I knew this was a cosmetic issue.

Check the Incoming Dial-Peer
Everything good

Check the CUE Dial-peer
Everything good

Check SIP Refer Messages
Few Questions on this one, really did not see them on my CCSIP Messages Debug

After some debugs I noticed that CUCM was not sending the SIP refers. But I also noticed that if the calls where started from within the company ring-back would play just perfect. At this point I suspected it had to do with CUCM.

Doing some research I found these few useful links and I will do my best to summarize them:

This one recommended changing a parameter in CUCM for H.323 trunks, but I currently have a SIP trunk with the Voice Gateway, so it didn’t apply https://supportforums.cisco.com/discussion/11261531/sip-trunk-no-ringback-after-transfer-pstn-call – However the good thing about this post is that it refers to a different post under the Cisco Support page, which was the one that helped get my answer – https://supportforums.cisco.com/discussion/11063241/sip-trunk-and-problems-ringback-tone#3370180

Reading this post I noticed that I had something I didn’t account for and this was the Annunciator resource from CUCM which made perfect sense. After adding this resource to an stand alone MGR and then adding it to my site MRGL made the whole thing work just fine.

Few things that could have work too that I considered doing before looking at the right place:

Add Ringback.wav file to the AutoAttendant on the transfer step.

Make the incoming Dial-Peer hit the AA before it would send the signaling to CUCM (Considering this one my next step on the configuration for fail-over purposes)

To conclude, these little issues have a great impact on the perception of clients, I also think that these are the things that make a Consulting Engineer better. It will be very nice to have all the gotchas out there (Which they are documented on the Cisco Support Site), and know all of them back and forth.

Thank you

About the Author:

Andres Sarmiento, CCIE # 53520 (Collaboration)
With more than 13 years of experience, Andres is specialized in the Unified Communications and Collaboration technologies. Consulted for several companies in South Florida, also Financial Institutions on behalf of Cisco Systems. Andres has been involved in high-profile implementations including Cisco technologies; such as Data Center, UC & Collaboration, Contact Center Express, Routing & Switching, Security and Hosted IPT Service provider infrastructures.

You can follow Andres using Twitter, LinkedIn or Facebook

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top