Well voip is totally legal in India & don't blame Mtnl for it as we all are using nicely and finely not even a single port is blocked by mtnl becoz they don't how to block Check your ATA adapter settings any networking configuration changed.Well i know many person using vonage on mtnl & yet to receive any complain form them.Which Vsp r u using , also network config ?? may be we cud help!!