With a busy line, the number of rings before a call is forwarded cannot be adjusted. Calls are forwarded instantly.
Call Forward No Answer (CFNA) can be adjusted with the Forward No Answer Timer service parameter. The default setting is 12 seconds. If you set it to 18 seconds, you get five rings before the call is forwarded.
On the Cisco CallManager Admin page, perform these steps:
- Click Service > Parameters.
- Choose the server IP address from the drop down menu.
- Choose Cisco CallManager.
- Scroll down to the Cluster Wide Parameters, and modify the Forward No Answer Timer field.
Note: This is a global parameter, so changing this value will affect the behavior of all phones. It cannot be changed on a per user or telephone basis. When changing this value be sure to do so for all CallManagers in the cluster.
For more information, refer to these documents: