W.a. using Skype on your cellphone/laptop or tablet.
I use Skype to call my mother daily to her phone in The Neth. (she does not have a comp.)
I pay a monthly fee of E 4,50 (something like that) for illimitate calls to all fixed phones in The Netherlands. Excellent quality (apart from Lima I called her from places like Chachapoyas, Pucallpa, La Paz). The only thing you need is a direct internet connection or a wifi/internet connection.
Skype offers a large range off all kind of subscriptions at (to my opinion) decent prices...