Core Issue
For a specific directory number, although Call Forward Busy (CFB) is set to direct calls to either a telephone number or to voice mail, the calls do not get forwarded when the original directory number is busy.
Resolution
Basic things to check for in this case are:
Use the following procedure to disable Call Waiting system-wide:
- From Cisco CallManager, select Service > Service Parameters.
- Locate the CallWaitingEnable parameter and change the drop-down selection to False.
- At the top of the page, click Update.
- Repeat the above steps for all Cisco CallManagers in a cluster.
Use the following procedure to disable Call Waiting on individual phones:
- Search for the directory number (or phone).
- Select the directory number at the left (if you searched by phone).
- Locate the Call Waiting setting on the page and change the drop-down selection to Off.
- At the top of the page, click Update.
- At the top of the page, click Restart Devices.
- Click OK. For further information, refer to Cannot Transfer Second Incoming Call.
- You can also check the value for "Forward Maximum Hop Count" in the Service Parameters. This should be a non-zero value. Set it to the recommended value (12).