We have a 3cx system with about 40 extensions. We have some Polycom IP 335's and some IP 550's. There are a few users who need to work in different buildings and share an office in one. For the phone in the shared office, I have the mac address entered in 'Phone Provisioning' for one of the users extensions in 3cx, and have manually added the second user's extension as line 2 in the Polycom web interface. We would like to have the phone play a different ringtone for each line. This is standard functionality on the Polycom phone, but we can't make it work with 3cx. Regardless of what we set the ring type to, it always plays the 'Low Double Trill' ringtone. I've tried taking a completely factory reset phone that is not provisioned in 3cx, and manually registering it to a 3cx extension from the phones web interface. Even with this bare minimum configuration, the phone will only play the 'Low Double Trill' ringtone. The only thing that does allow us to set a different ringtone, is to connect the phone to Asterisk instead of 3cx. Does anyone know what 3cx is doing that is preventing us from setting a ringtone on our Polycom phones? We are running version 4.0.10 of the Polycom firmware as is recommended by 3cx. I tried updated to the latest 4.0.12 firmware on one phone, but that did not make a difference with this issue.