Calls between IP phones within a Cisco CallManager cluster take a long time to set up due to an interdigit timer issue and improper dial plan

[TCC_2]

Core Issue

A significant delay of up to ten seconds could occur during a call setup between two IP phones registered in the same Cisco CallManager cluster. This is primarily due to an overlap in the dialing plan. For example, an IP phone with the extension 555 and a call park range of 555xx could exist in the dial plan.

Resolution

Cisco CallManager relies on the interdigit timeout to allow the user sufficient time to dial the number. If overlaps in the dialing plan cannot be avoided, you can shorten the interdigit timer value by performing these steps in Cisco CallManager:

1. Select Service > Service Parameters, and select server.
2. Find the TimerT302_msec* parameter, enter a value of 6000 and click Update. This sets the interdigit timer to six seconds.
3. Have the users test the phones and adjust as necessary.

For more information, refer to these documents:

• Delay in Call Establishment: Configuring the Interdigit Timeout

• Cisco 7900 IP Phone FAQs

If the delay is observed while dialing local Public Switched Telephone Network (PSTN) calls, refer to User experiences a delay in call initiation when making local calls