UCCX Agent Cannot Transfer Calls

[Mustain]

Hello all,

Please help, maybe here someone once had the same problem. Currently, when I try to make a call to the Agent via UCCX, the agent can receive the call, but they can't transfer the call to another extension, the transfer button on IP Phone doesn't work.

This condition occurs when SIP Trunk in CUCM has unchecked MTP Required. However, if we select the "MTP required" in the CUCM SIP Trunk, the call can work properly.

This is the flow of the call,

ITSP -> CUBE -> SIP -> CUCM -> UCCX

Thank you in advance.

[Elliot Dierksen]

What do you mean by "does not work"? There are several ways that the call could fail, and the the kind of failure you get says a lot about the cause. I would normally say to check DNA (dialed number analyzer) to see if it is dial plan, but that sounds unlikely given that a change in a SIP trunk setting changes the behavior. It would also be helpful to know more about your topology. I am inferring that the CCX agents are in one cluster, and trying to transfer calls to IP phones on another cluster. Is that correct? More information is almost always better when you are trying to get help from someone not familiar with your environment.

[Mustain]

Thank you for your time. So the call flow is basically like this below.

ITSP> CUBE -> CUCM -> UCCX -> CUBE -> CUCM.

The call is received by the agent, and then this agent tries to transfer the call to an extension in the same cluster. The problem occurs when I tick the "Media Termination Point Required" checkbox option in the SIP Trunk. However, if I uncheck the box, the agent can't transfer the call and the call will be closed.

[Elliot Dierksen]

That call flow does not make sense at the end. The only place where UCCX can talk directly to the CUBE is as part of an outbound campaign. That shouldn't be the procedure for transferring a call as there would be no need to transit the CUBE. What dialed digits are the agents using? Can they place a direct call to the extension in question? They should use their IPCC extension to place this call, not their personal extension (if they have one).

[Elliot Dierksen]

I was thinking about this a little more, and I think there may be a problem in your CUBE config. Do you have issues when an IP phone user with a DID gets a call, and then attempts to transfer it? What forcing an MTP on the SIP trunk to the CUBE does is that it locks media to that MTP facing the CUBE. The audio stream is torn down, and a new one built when a call is transferred. Perhaps the media options (UPDATE, RE-INVITE) are not working properly with the ITSP. It could also be that you are sending network MoH during the transfer (this is the normal operation). The MoH is a send only stream, and some ITSP's do not like that. I have had to do SIP profiles that change "sendonly" to "sendrecv" in the SIP messages. I would suggest you do a "debug ccsip mess" in the CUBE and trap the messages during a call drop. I suspect that will give you a better idea of where the problem lies.