When a Skinny Call Control Protocol (SCCP) analog phone that has a message waiting is left off-hook, the stutter tone does not play. This problem only occurs with these Cisco IOS software releases:
This issue is documented in Cisco bug ID CSCsh47703.
As a workaround, downgrade to an earlier software release, since the problem only occurs on these Cisco IOS software releases:
Note: If 9xxxx is dialed for an external call, the stutter tone sounds if there is a message.
For downloading the IOS software, refer to Cisco IOS Software Download