I want to write a 3PCC to setup a call between to softphones registered with my 3CX server. When I issue a INVITE, I am receiving a request for Authentication (407). Regardless of what credintials I send, I continue to receive the 407. In this case, what would the right credinitials be ? The ADMIN user/pw or the credintials of a specific registered soft phone ? Any advise would be helpful.