Error 407 Proxy authentication required indicates that the client must now authenticate itself with the proxy. this error is normal in networks where authorization is enabled (most networks) and can occur once per SIP request and is generated by the network. If you are continuously getting this error, either you have entered incorrect login information (username/password), or your account has not been provisioned or set up properly.
If you are using one of our retail products, verify that your account credentials have been properly entered. If the problem persists, we recommend that you follow up with your VoIP service provider.