Cell phone usage has become relatively widespread in Cuba in the last few years. Normally a recorded message will inform you of phone number changes. Etecsa telepuntos have air-conditioned phone and internet terminals in almost every provincial town.
Check with your service provider to see if your phone will work (GSM or TDMA networks only). International calls are expensive. You can pre-buy services from the state-run phone company, Cubacel.
You can use your own GSM or TDMA phones in Cuba, though you'll have to get a local chip and pay an activation fee (approximately CUC$30) at Etecsa telepunto. Bring your passport. There are numerous offices around the country (including at the Havana airport) where you can do this.
Costs run between CUC$0.35 per minute for calls within Cuba, CUC$0.10 for texts. You pay the same amount if a fixed line calls you. International calls start at CUC$1.10 per minute. To rent a phone in Cuba costs from CUC$8 plus a CUC$3 daily activation fee. You'll also need to pay a CUC$100 deposit. Charges after this amount to around CUC$0.35 per minute. For up-to-date costs and information see www.etecsa.cu.
Etecsa is where you buy phonecards, use the internet and make international calls. Blue public Etecsa phones accepting magnetized or computer-chip cards are everywhere. The cards are sold in convertibles (CUC$5, CUC$10 and CUC$20), and in moneda nacional (five and 10 pesos). You can call nationally with either, but you can call internationally only with convertible cards.
You will also see coin-operated phone booths good for Cuban pesos (moneda nacional) only.
Local calls cost from five centavos to 75 centavos per minute depending on the time of day and distance. Since most coin phones don't return change, common courtesy means that you should push the 'R' button so that the next person in line can make their call with your remaining money.
International calls made with a card cost CUC$1 per minute regardless of destination.
Hotels with three stars and up usually offer slightly pricier international phone rates.