I think it used to be the case that one of the internet service providers (Etisalat) blocked it, while the other one (Du) allowed it. (It was a perhaps unadvertised advantage of Du. An ISP USP?)

In some hotels in which I have stayed it works, while in others it does not. Though it seems to have worked more lately; maybe the blocking is sporadic and/or some hotels have their own systems or constraints.