Calls Being Dropped When Transferred

[mclason01]

I have an issue where calls that are transferred to an external number are being dropped.

Example: A customer calls in to the call center, tell us they would like to make a payment, so they are forwarded to a self-payment center (external).

The agent presses the transfer button, dials the payment center, hears the call get picked up and then presses the transfer button, completing the transfer. The problem is that instead of the transfer happening, the original caller gets hung up on. 

I was made aware of the issue, so I did some testing, and discovered the following.

- The drops only happen with 800 numbers, like (866) XXX-XXXX, or (877) XXX-XXXX, and only get dropped about 50% of the time. The other 50% of the time the calls make it to the self-payment center successfully.

- I am able to transfer calls internally, or to non 1-800 numbers successfully 100% of the time.

- Calls to these numbers only get dropped when they are transferred. I can call these numbers from an internal VoIP phone, or from a mobile, and get through 100% of the time.

Thanks for any help!!

[Chris Deren]

What kind of PSTN technology is used for the external dialing (SIP, PRI, etc)? If SIP please provide "debug ccsip message", if PRI provide "debug isdn q931" and identify the number transferred to and original caller number, and transferee number.

[Wilson Samuel]

I have had a similar issue but with DTMF (SIP Trunk w/CUBE).

You will be amazed to know that, once you report this to Telco, it may just "miraculously" get solved, and they would have done "nothing" on their end.

However, please ensure that, you raise a trouble ticket with your telco first and share the captured debug here as well :-)

HTH

[mclason01]

Thank you for your replies! This a SIP Trunk w/CUBE. I was on the line with Cisco for quite a while. They found that our CUBE was sending out a flood of update requests, which caused problems with the service provider. Below is the summary of what happened. The problem appears to be resolved.

Problem Descpription: Call transfers being dropped intermittently.

Action Taken: Checked the Traces and found Update message was being sent continuously to the provider from Cube for non working call. Traces for working and non working  calls are attached with Case.

Issue fixed using below command.

#voice service voip

#sip

#mid-call signaling passthru media-change

[Mohammed al Baqari]

Hi,

Please share your call flow along with use protocols. Call dropping during transfer most of the time is due to mismatch in call signaling and many times resolved by deploying MTP (but necessary the case here).

Once we get more details we can drill deeper for more logical approach.

[mmaamm238]

Hi,

I have a problem with call transfer. I have SIP trunk with ITSP. When I want to transfer an external call from 7965 to 7945 it drops but from 7945 to 7965 is successful. Both phones can call to each other and outside without problem. My CUCM version is 11.5.

How can I troubleshoot it? Is it signaling or codec problem?

[Roger Kallberg]

As your question is off topic to the OP and this post is from way back in 2015 I would recommend you to create your own post to ask your question.