SARK V4.0.0 siptrunks
Introduction
You will often find it necessary to talk to downstream PBX systems; either in your company or if you are running a boutique ITSP service using SARK. Here is a setup guide for such trunks.
Upstream SARK box
If you will only ever need to support a single trunk to the downstream PBX then you can simply set up a "direct connect" trunk with no registration or login credentials. You will need to ensure that you restrict access in the SARK firewall or your perimeter if you wish to run this kind of a setup otherwise you will, in effect have an open proxy and anyone will be able to send calls through your PBX. All that is needed in SARK is a general sip trunk with the asterisk peer set as follows
type=peer context=internal host={ip addr} qualify=yes canreinvite=no insecure=port,invite disallow=all allow=alaw allow=ulaw