This is an old revision of the document!
Unbricking Cisco IP phone
Core Issue
After the default Skinny Call Control Protocol (SCCP) firmware of the 7912G IP phone is changed to Session Initiation Protocol (SIP) firmware and the IP phone is powered on, these issues occur:
- The hold button is red.
- The menu button is green.
- The display window is blank.
This indicates that the phone firmware is corrupted.
Resolution
If the menu and hold buttons are lit red and green respectively, the phone is in recovery mode. It is possible to return the phone to an operational state.
Complete these steps in order to attempt to recover the phone:
1. Connect a PC to the same network as the phone.
2. Use a network sniffer in order to verify if the phone is operational.
Does the phone transmit any IP packets or request any files from a Trivial FTP (TFTP) server?
Yes The phone is operational. Proceed to step 3.
No The phone is no longer usable and can not be recovered.
- Look at the network sniffer log and note this information used by the phone:
Software image file name
TFTP server IP address
4. Put requested software image file on the TFTP server from which the phone requests it. The phone requests the last software image file that it
downloaded or attempted to download, if the information is available. Or it requests its default recovery software image file.