Hello, Are you looking for an answer to how the phone will register and to prevent it? Typically, it will use the TFTP address that the phone receives either in the DCHP scopes option 150 normally in a voice VLAN or if it set manually on the phone in...

Something you can try if you are still having this issue...I ran into a similar issue when we started using G711 renegotiation for specific callers. The solution ended up being on the RightFax server. As Tanner notes above, the Sip Session Expires Ti...