I posted about my phone disconnecting every 15 minutes from my new provider Nextiva. After hours of testing, it appears it is only happening with calls that stay on their network. I have 5 DIDs with Nextiva and anytime I call one of them, disonnects every 15 minutes. Works fine to any numbers not on their network. I've even called internally on my PBX (extension to extension) and it works fine. They put a trace on and this is what they'came back with. Any guidance as to if there is something on my 3CX PBX I Can fix? It is version 10, SP3. Again, this is only happening on calls over Nextiva's network between my DID's. Heres what happens When the refresh time hits (normally around the 15 minute mark) we send you an invite to refresh the call. Most of the time the invite is simply responded to with a 200OK from your PBX and the call is good to go for another 15 minutes. What appears to be happening here though however, is when the invite is sent to your PBX to refresh the call, instead of sending back a 200OK, you send back a 407 Proxy Authentication Required, a message that should only be sent by US not you. Your PBX basically asks US to authenticate with IT, and since we dont get a 200OK in response to the refresher invite as we should be, our server thinks there is no valid source to establish the refreshed call to on the other end and sends a disconnect message to your PBX telling it that we have ended the call (a sip BYE message).