[Asterisk-Users] Unblocking incoming SIP

[Thor Atle Rustad]

I have just set up my first Asterisk, and I have the basics up an running. 
I have set it up with two SIP phones only. I can call between them, and I 
can call out to FWD phones. However, on receiving calls from FWD, my 
Asterisk blocks the calls with the following message:

May 30 20:19:24 NOTICE[180236]: chan_sip.c:6397 handle_request: Failed to 
authenticate user <user> <sip:fwduser at fwd.pulver.com>. Obviously, I want 
FWD users to be able to call me without my registering them first.

Any suggestions would be appreciated.

Thor