Core Issue
When a user is on the first line and another call arrives on the phone, since the first line is busy, it is configured to activate the second line. However, the call alternates between getting a busy signal and hitting the second line for Call Forward Busy (CFB). This issue is observed with any internal or external calls and Cisco CallManager that runs version 3.3(2)spC. Also, both lines are in the Null partition.
Resolution
This problem is a known bug discussed in Cisco bug ID CSCeb26362.
This problem can occur if the publisher and subscriber databases are not synchronized. The workaround is to restart the subscriber each time the problem occurs so that the databases are synchronized. Cisco bug ID CSCeb26362 has been fixed in Cisco CallManager versions 3.3(2) ES29 and later. Therefore, upgrading Cisco CallManager to version 3.3(3) resolves the issue.
