U-verse IP-based voice service is being introduced in the Austin area. So those of you who wonder when incumbent service providers will get on the VoIP bandwagon have an answer. VoIP makes most sense for an incumbent provider when the basic service package includes other IP-based video services.
Even when IP isn't extended completely to all the end points, the adoption pattern will mirror the ways IP and optical fiber was introduced into the rest of the network. IP made first sense in the network core. So did fiber. Over time, fiber extended into the metro trunking plant. That same sort of thing will happen as soft switches replace older TDM switches.
VoIP features will be made available at the central office, with media gateways between the end user analog equipment and the CO. Over a period of time, the gateways will migrate deeper into the access network.
But there will not be a complete flash cut to VoIP as the voice platform until some critical mass is reached. At some point, half the customers will be buying IP-based video or data services. Sometime around then, it starts to be feasible to decommission the older networks.
But not much before then will it make lots of sense.