It is not legal for Etisalat to block the VOIP. Call and threaten them and ask them for their right to block it. Ask them to send the rules and regulations for use of their internet.
Write a mail to CEO of Etisalat and have him explain their right to block it and have him explain why they believe it is a security issue in Dubai and not in the rest of the world.
They are so full of ****.
They have no right to do it.