Yes , it is legal in oman.....you can click on LINK for much information
Dec 17, 2009
– CashU provides merchants with a solution where
they can sell their goods and services on the internet, including
virtual products (such as cheap VoIP calling credit) or telephone
services (DID local access numbers) that require micro payments.
Merchants pay no setup or installation fees and integrating cashU is
quick and simple.
This move is intended to strongly compete with other residential
VoIP providers such as Skype, Vonage, Ooma, Betamax, Gizmo and Google
Voice by giving users in Middle Eastern countries the capability to
enjoy the benefits of Tpad VoIP where credit card penetration is
extremely low. This is especially true for users in Egypt, Jordan,
Kuwait, Nigeria, Oman, Palestine, Qatar, Saudi Arabia, Sudan, Syria,
and the UAE.