Hoping someone has run into this... I have 3CX v12, and Cisco SPA504G phones. I can create a new ext, and then perform a factory reset on the phone. The phone will display the right name, number, and evern download and update the firmware. However it never registers in the system. Using wireshark on the server I can see the SIP traffic and one packet stands out... SIP 406 Status: 403 Invalid password provided I have tripple checked all the passwords related to the ext, any thoughts?