This is a bit obscure, but I have managed to set up an Asterisk PBX server with some old Cisco 7910 phones. They have their idiosyncrasies though, so here are a couple of tips I’ve picked up along the way:
- To edit the settings on the phone (e.g. change the TFTP server), you need to unlock the settings by pressing “**#” and then the Settings key. Doing so should make the padlock icon turn to unlocked.
- You can then edit the editable settings by pressing the “*” key, with the “#” key saving your changes.