Technically Skype is illegal in the UAE - where there are only 2 mobile and internet providers Etisalat & Du. But there are ways round it. Rules were made to be broken. The 2 'dominators' are talking about legalising it soon - but they'll probably charge for it.
Not sure if it can be done on a mobile phone in UAE however?? Someone will know...
The best answer might depend on which country you're based in - Bahrain & Kuwait or Qatar or Oman all will have different phone companies.