If you have phones using the UNIStim software, they must be in version 0625C39 or higher. Firmware upgrade from UNIStim to SIP can only be done via TFTP. That's why this plugin has some support for TFTP.

You might have to set MODE to FORCED in 1220SIP.cfg/1230SIP.cfg if you want the phone to upgrade its firmware. There seems to be some mysteries around why the phones don't want to upgrade their firmware sometimes.

There's currently a limitation with SIP NOTIFY 'check-sync', where the user needs to press the key on the phone for this to work.