SIP call forwarding


I needs to forward incoming sip call to other country number

please guide how i can achieve this. Don’t i needs to register destination sip number first in SIP.conf in asterisk ?

Is it possible to terminate coming sip call to any other mobile/landline even when its not registered in our asterisk server?

please shed some light on this

what other services, ports needs open, other things to take care of

I’m newbie to asterisk hence don’t have full clarity on the call flow

waiting for the response

Thanks in advance