The Cuban government simply doesn't allow it! They have a full and comprehensive list items which are NOT allowed - and 'can' include mobile telephones as well.
In general, the 'normal' cuban citizen is not allowed even internet access, either!
Tourists can access the internet from the hotel computers that may or may not be available?!
Anyhow the list of things you CANNOT take to Cuba:
* Electric power plants (generators)
* Video equipments of all types, notwithstanding the country of manufacture or brand, including those produced and sold in the market as built-in accesories for other equipments (VCR, DVD, Play Station 2, etc.) Shall be exempted from this prohibition foreign diplomatic personnel, Cuban officials having stayed abroad for over a year, as well as individuals authorized to import household m�nage.
* Radio transmission equipment and transceivers;
* Wireless telephones that operate in bands different than 40-49 MHz and 2,4 and 5 GHz
* wireless microphones
* Wireless Facsimile terminals;
* Telephone switchboards and equipment;
* Professional Radio and TV receivers differing from household models;
* Geo-positioning equipment (GPS );
* Satellite receiver antennas and stations;
* Satellite communications ground stations.
* Freezers of more than seven cubic feet of capacity;
* Air conditioners;
* Electric kitchens and furnaces - of all types, models and capacities
* Electric ovens - of all types, models and capacities, including micro waves.
* Electric showers - of all types, models and capacities
* Electric fryers - of all types, models and capacities
* Electric water heaters
* Electric irons without sprinkler consuming over 290 watts/hour or electric irons with sprinkler consuming over 703 watts/hour
*