You can make and receive calls on it, but if you try to transfer a call to it as soon as you hang up and complete the transfer it disconnects. Or if you do a blind transfer it hangs up as soon as you answer.

I've tested with a 3CX's Windows SIP phone using the same extension and it works fine, so it's got to be something between the Toshiba and the Panasonic. Any thoughts?

Is there any firmware updates available for the Panasonic that may help with this?

Also, it does seem to cut out on transmit intermittently during long conference calls.

Toshiba Sales & Installation Tech