I have a few voice gateways set with the following access number:
vg1:
sp2(sip.callwithus.com:5060)
vg2:
sp2(tampa.voip.ms:5060)
However, I just found I had to config something (basically anything) for SP2 before I can use it for my voice gateways. Currently my SP2 is connecting to my Asterisk server and I can route calls to vg1/vg2 without any problem. If I drop the configuration for SP2 in Device Configuration page, then I will get an error message saying service is not available when I try to go through vg1/vg2.
Is there any reason behind this strange behavior? It seems to be a bug to me, since when I am trying to access vg1/vg2, it got nothing to do with my Asterisk. My theory is if I drop SP2 configuration, then SP2 became disabled and cannot be used by any voice gateways. This seems to be an unnecessary restriction. SP2 should be re-enabled when a voice gateway is trying to utilize it.