Case Study: Cisco Phone 7942 unexpected auto-call/auto-dial

Problem Description:
This is an actual ticket escalated to our team.

User reported that his Cisco IP Phone automatically dials a number once he picks up the handset of the phone.

HW/SW Versions:

• Cisco IP Phone 7942
• SCCP42.9-2-3S
• CUCM 7.1 (7.1.5.33900-10)

Troubleshooting:

• Same behavior is observed when pressing the speaker button;
• Same behavior is observed when pressing the headset button;
• Only one number is being called consistently;
• IP Phone is registered correctly in CUCM;
• Resetting the phone has stopped the auto-dialling.

Root Cause:
After some research, we found the bug documenting this behavior:

CSCtz29414 - 7942/7962 - Call History is Auto-Dialed When Pressing Speaker Button

Symptom:
When a 7942/62 phone is populated with call history records (e.g. received/placed/missed calls), the endpoint will auto-dial the number contained in its call history when the speaker button is pressed.

Conditions:
IP Phone Call History contains Received/Placed/Missed Phone number record prior to pressing speaker button to go off-hook. Phone will continue to auto-dial the number listed in Call History once error condition is experienced.

Workaround:
Reset IP Phone to clear error condition

1st Found-In:
9.2(3)

Fixed-In:
9.2(3)ES7
9.3(1)TH2.2
9.2(3)MN1.22

Workaround:
As per the bug above, reset the phone

Permanent Fix:
Upgrade the phone firmware.