Will the major telcos take the opportunity to block other specialist suppliers of VoIP service for "security", and try to inhibit switching to a different provider?
At the moment, if you have an Internet service, you can get digital phone lines with no line rental, low call rates, even free calls to some other VoIP numbers. The telcos are not currently worried by the few geeks that use VoIP for domestic service, but this could change.
At the moment, for calls not covered by a package, the telcos will charge a connection fee for each call, and have minimum call duration of a few minutes. If you want to dial across the pond, they will purse their lips and say, "Ooh, long distance gov, takes a week to get there by steamboat, so gotta charge you accordingly." They will want to ensure that roadblocks to competition remain, so the existing business models for call charging and line rentals are not undermined.