Resetting Cisco Phone

Issue/Question

Phone display stuck on registering

Missing functions such as transfer, hold

No dial tone

I cannot make or receive calls but the phone will ring

Phone is unresponsive

My voip phone is taking a really long time to make phone calls. There is a long pause before it will dial out and connect the call.

Environment

• Cisco VoIP phone
• 8851

Cause

Resolution

Power cycle the phone

1. Disconnect phone from the network
2. Wait 10 to 20 seconds
3. Re-connect phone to the network
4. After reboot finishes test functions

Reset phone to factory defaults

Note: Any phone customization and preferences will be lost

1. Press 
2. Admin Settings
3. Reset settings
4. All settings
5. Phone should reboot
6. After finished, test functions
7. If you are unable to do the steps above because the screen does not come on
   1. Unplug the phone from the network cable
   2. Leave the phone off for 5 seconds
   3. Hold down the # while plugging the phone in
   4. If the screen does not come on, do the same steps with the 0 key