Somebody use VPN to solve the VoIP Blocking issue. But it seems not a good way to solve the voip blocking issue. Because VPN will take more bandwidth and will take effection on the Voice Quality
Currently I am using the VGCP, a new solution to solve the VoIP Blocking issue. Following is theirs website:
If any of you have interested, you may try to use it to solve your VoIP Blocking problems. Thanks.