No incoming calls

Hi. Could anyone help
I have two different SIP phones (e.g. 90133 and 90019) behind NATs and Asterisk server.
So, both phones can dial via Asterisk to external world, and, moreother 90133 can call 90019, but not vice a verse:
90019 can’t call 90133.

In Asterisk logs we have smth. like that:

Reliably Transmitting (NAT) to 80.253.232.106:5060:
SIP/2.0 403 Forbidden

So, what is the problem in general?

Thank.

I believe that it means your authentication failed. Check to make sure you have the correct username and password specified in sip.conf.

Dan