If cell companies can play songs to the caller, instead of ringing, does that mean they connected the call? If you get a lot of LD inbound, are you guaranteeing the caller has termination fees? I guess they must. That is revenue for the cell company each time.

VOIPo could be accused of trying to get additional revenue by the extra call handling. Voicemail likely has the same termination costs to the caller's service.

I expect this involves a different method of internal call routing, and is not just a hand-off to a switch. (Wish I were more technically savvy about this.)