I have a problem with incoming calls with my VOIP provider (callcentric.com) When I signed up a few weeks ago, all of their servers used standard port (5060) and I was able to make calls (in/out) just by enabling SIP ALG option.
About 3 weeks ago, Callcentric was a victim of DDOS (and still recovering) Somewhere around that time CC switched to use DNS SVR (from DNS A) to help distribute the load.
Unfortunately (for me) the new servers also use non standard ports:
_sip._udp.callcentric.com. 2 IN SRV 20 0 10123 alpha11.callcentric.com.
_sip._udp.callcentric.com. 2 IN SRV 20 0 10123 alpha12.callcentric.com.
_sip._udp.callcentric.com. 2 IN SRV 20 0 5080 alpha1.callcentric.com.
_sip._udp.callcentric.com. 2 IN SRV 20 0 5080 alpha2.callcentric.com.
Ever since this change, incoming calls started randomly getting rejected by ZyWALL. The only way I could make it work, was to add ports 5080 and 10123 to the SIP signalling port list (see attached pic) Obviously, this is not optimal as I will have to keep an eye on ports used by CC.
Is this the right way of doing it?
BTW, this ZyWALL USG50 3.0, and OBi100 ATA.