I have an account through ipcomms and I can input my SIP user info into a software sip dialer and dial all day long no problem0000, but when I plug it into my GVX phone I just get a busy signal when I dial. I have IPCOMMS on chat with me trying to work it through for several hours yesterday to no avail.
I have read that Frontier can be dicey with voip other than their own solution, but if that were the problem then I wouldnt think the softdialer would work either.
I have udp 5060, 20000-60000, and I believe a few others opened inbound - nothing being blocked outbound. On the IPCOMMS side of things, I do see the device go REGISTERED - So I know we are at least getting that far.