A news account out of the UK thinks the incumbent carriers are trying to slow down VoIP.
Just like downloadable music was happening in the 90s, you can’t put the genie back in the bottle. VoIP is here and it is working and people are using it. The fact that some telcos are being slow to move in the direction of deployment, or they have not figured out integratrion is wrongfully viewed as seeking to stop VoIP.
On the other hand, port blocking of VoIP is clearly a defensive move.