I subscribed to Sipphone about a month ago and bought a DID in another city (Cleveland) so my sister could call me toll-free. Incoming calls are free on Sipphone and she lives in the Cleveland metro area so the call is free for her.
The problem is that she rarely can complete a call. When she does, it takes several attempts. When she dials, my phone will ring once or twice. She hears a couple of rings and then either gets a message that says "All circuits are busy. Try again later," or she simply gets a fast busy signal. I rarely make calls from that line. The other line is configured for another voip service. Occasionally I will be unable to complete an outgoing call through Sipphone. I get a recording that says the call can not be completed as dialed.
I assume this is a Sipphone issue? I never have problems with my other VOIP provider.