Forward the SIP request to the given
destination. This has the format of [proto:]host[:port].
Host can be an IP or hostname; supported protocols are UDP, TCP and TLS. (For
TLS, you need to compile the TLS support into core).
If proto or port are not specified, NAPTR and SRV
lookups will be used to determine them (if possible).
If destination parameter is missing,
the forward will be done based on RURI.
Example of usage:
forward("10.0.0.10:5060");
#or
forward();
http://openser.org/dokuwiki/doku.php/core-cookbook:1.2.x#forward_destination