Originally Posted by
tev9999
I believe that the internet providers can/do block the ports and or sites that allow VOIP to work.
It's not port blocking. Skype, for example, will try lots of ports, including port 80 and 443. Blocking those ports would not be wise.
Originally Posted by
tev9999
It should not be difficult to block at the router or site filter level.
Have you tried it? Although corporate SIP and H.323 setups often use well-known ports, ask the engineers at Sandvine, or Bluecoat about "how simple it is to block VoIP" and you'd hear an earful. It's a battle between those who want VoIP to go through and those who want to block it.