After burning through the free 60 minutes on OBivoice, and seeing no quality issues, I opted to sign up for a year. Part of my justification was increasingly frequent incoming calls that would only ring my cell, but the OBi box wasn't ringing. Switching to OBivoice seems to have solved that (so far). However, I still get occasional calls where NONE of the forwarded phones will ring until the caller's fourth ring - at which point I can't get it before VM picks up.
Anyway, I've convinced my father to make the jump to OBivoice early too. However, when we call each other on 4 of 5 calls, there's at least a 2 second delay between us. I've only noticed this when talking to him.
I've also had one or two incidents of choppy/motor boating. Just now I tried calling him, and I got a "the person at extension XXXXXXXX [his local OBivoice number] is unavailable". We have both disabled OBivoice's voicemail features and set the ring time to 90 seconds.
I'm starting to doubt the service. Guess I'll send them a note.