Calling is possible with all common cell phones in Cuba. If necessary, a special activation of your own mobile phone provider for Cuba is necessary, as the roaming charges are very high there.
Public prepaid WiFi is available at almost all central public places, hotels and marinas.
VPN tunnels do not work any more since december 2020. Internet telephony like WhatsApp work without restrictions via the public WLAN. Price approx. 1.00 CUC / h. You can use it to dial in multiple times, i.e. split the acquired hour into multiple logins, for example to only access emails, only a few minutes are necessary. The WLAN card lasts a whole week.
The cards are available in the ETECSA shops or on the street (in front of the ETECSA shops or at the hotspots) from the "WiFi dealers" who sell the cards for a small surcharge.
The speed is fastest early in the morning (Cuban time). In the evenings, many Cubans sit in public places and use the Internet. Then the connection speeds are very low or you can no longer log in at all. We recommend calling abroad with the prepaid WLAN card via WhatsApp. We also use this regularly and it works very well.