Bolivia has three mobile phone providers, Entel, Tigo and Viva. All three have outlets in virtually every neighbourhood of the major cities. Internet cafes are becoming rarer with the proliferation of smartphones making internet access more accessible. However, you can still find a cybercafé if you are looking, they usually cost around 3Bs/hour, or about $0.50 per hour.
There are still traditional public phones, but you can also make local calls for 1Bs ($0.15) from mobile phones in kiosks.
If you are staying for a while, you should consider buying SIM cards for your phones. They are quite cheap and you get good network coverage in all the major cities. Entel sells cheap international calling options for its SIM cards. For example, you can buy 10 minutes for Bs20 (to be used during the day, they will be automatically disconnected after expiration). You will need to register the SIM card with a local telecommunications office. You will need a photocopy of your passport and the mobile phone you will be using.