The state-run telecommunication company Etecsa runs offices (daily from 8:30 am to 7:30 pm) and public card phones that you can use to get internet and to do international calls.
Etecsa Internet cards cost 1 CUC for 1 hour of internet connection (about $1.20). If you are travelling for 1 or 2 weeks, you can get cards for up to 5-hour. These are valid for 30 days from activation.
Making phone calls from Cuba
If you need to make a phone call, use the dialling code (with zero) for domestic calls, for calls abroad the dialling code 119, then the country code (UK 44, USA 01), then the local dialling call without the zero.
Dialling code for Cuba: 0053
If you are calling a mobile phone number, you just need to dial 5 before the rest of the mobile phone number.