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CTI OS desktop agent cannot answer call

Hello All,

I am seeking a suggession on a issue which seems to be lying with network.

Agents are located in different location and all remaining Cisco components like ICM, CVP and CCM are in data center.

Agent succesfully logs in via CTI os Dsktop agent and IP phone, but when call is transferred, its state fluctuates between ready and reserved. CTI OS desktop agent never goes to talking state and call never lands on IP phone.

Network team claims nacessary routing and firewall ports are already open.

Seeking suggesion to further isolate and what logs/traces can be collected to identify the source of issue.

Tried 1 test agent login in data center and observed that in data center call lands to agent succesfully.

Any directions/pointers?





Hi Kailash,

Could you please check the below points:

1. Check if you associated the Agent phones to CCMPG user.

2.Symptom: Agent receives calls, but loses them after a few seconds before they can be answered.

Possible Cause The Ring No Answer feature is probably set on your ICM system. Open the ICM Configuration Manager and increase that value or disable it all together. (Refer to the ICM Administration Guide for Cisco ICM Enterprise Edition for more information on how to configure the Ring No Answer feature.)

3. Make sure the CSS and partitions are proper.

Also refer the below troubleshooting guide for more information,

Hope it helps,


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3 above.

The typical problem here is that the SIP trunks from CUCM to the SIP Proxy servers (or to your Call Servers, if not using a SIP Proxy)  and the problem phones are not in the correct partition/CSS that enables the call to be set up.



Hello Kailash, Ancoudh, Geoff,

I faced the same issue twice. Our platform is up and running for serveral years (now running UCM - UCCE - CVP 8.5.2)

. Suddenly, some of the agents could not answer calls anymore . It was getting worse and worse. We fixed the issue by resynchronizing the bandwidth on the locations on the call manager. The system was running fine a few seconds later. I suspects defect on the process that calculates the BW. Please note that it happened twice after a call manager configuration update (not really related to UCCE objects). Last change we made was deploying EMCC feature on the call manager. I do not have evidence, but I think that when adding or updating Trunk or Location, something wrong happened. Do you know in which scenario cisco suggest using BW resync feature ?

Best regards


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