I have an exernal gateway and want to configure in one Asterisk server, but I wish that another Asterisk get this traffic to bill. Is it possible?
The second Asterisk will not to connect with SIP extensions using user and password, should connect with another form connection, that I don’t know how.
You can interconnect the asterisks via IAX.
I have one server managed to me, and I have a SIP extension of another Asterisk server, is it possible forward a call behind this extension, only once ?
“SIP extension” doesn’t mean anything to Asterisk.
If you mean can one Asterisk emulate a SIP phone connected to another Asterisk? That’s no different from connecting that other Asterisk to an ITSP. The same limitation applies, i.e. you can only emulate one phone if the remote Asterisk is identifying calls by IP address (type=peer, with chan_sip, and you will only be able to distinguish incoming calls if dialled digits, distinguishing the called device are forwarded.
Of course, if all you really want is a tie trunk, then this is over-engineering.
How can I make the settings in Asterisk server 1 to connect in Asterisk server 2 only with this informations, user, password and domain ?
The same was as you would to an ITSP.