Question: If I bring a tri-band phone to Cuba and buy a sim card in Cuba, can I call outside Cuba, receive calls from outside Cuba and is it possible to use skype?
Answer: Yes and no. Yes, you can RENT a sim card via Cubacel. However you cannot use Skype, even over a wifi internet connection in a Cuban hotel.
In a telephone consultation with Cubacel, the business arm of ETECSA which offers mobile telephone services in the country, they said that for your tri-band phone to be activated for use in Cuba, it must be GSM working in the 900 MHz band width. It must also be decodified (that is, free of any commercial company). If it meets these two criteria, it will be able to make and receive international calls while you are in Cuba.
SIM cards (pre-paid with a certain amount of time on it) are available from all Cubacel offices and can be purchased for 10, 20 or 40 CUC each. The sim card itself cost 3 CUC a day to rent and must be turned in when you leave the country.
You will find Cubacel offices in both Terminals #2 and #3 at the José Martí International Airport in Havana.
Cubacel’s website is www.cubacel.cu
There are also various ETECSA “telepuntos” located elsewhere, including in some hotels, where you can get SIM cards.
If you would like to buy a sim card as a foreigner in Cuba you must have at least Temporary Residency or you can try your luck on www.revolico.com which is an online classifieds service where you can sometimes find Cubans wanting to sell their sim cards.