VOIP / Asterisk - handle_response_invite: Received response: "Forbidden"

WARNING[0000]: chan_sip.c:11111 handle_response_invite: Received response: "Forbidden" from '"Extension Name" sip:EXTID@VOIP_HOSTNAME

This usually means that the provider you use for your VOIP server is sending a "Forbidden" response back to the server. This on the other hand means that they are blocking those calls/numbers.

In most cases, this happens when you attempt to call premium charged numbers, because these tend to be disallowed due to these being open to fraudulent use.