Does restarting IPVMS (IP Voice Media Streaming App) help anything when you restart it? It sounds like the call is not going into ringing state so you cannot press transfer a second time on the phone to complete the transfer. To really determine the exact call flow, since you said call center, do you have contact center enterprise or express? Are transfers initiated from CAD through CTI or on the phone itself? Are transfers going back through contact center (CVP, etc)? If you can capture a problem transfer with Cisco CallManager and possibly CTIManager traces set to detailed I can take a look if you attach them to your post.
Dear ther is No any UCCX . Its only simple Hunt Group and Transfer the Calls from PSTN to internal Ext. its working for 15 user in group.
when i restart IPVMS its going to working some time. i m not sure its right service to restart for this happening.