Pulse Telecom - any reviews?

[Codrin]

Hi. I was recently relocated to the USA and I’m looking for a long distance phone company to call my relatives and my friends in Europe. Someone told me that Pulse Telecom could be an option. This company provides international phono calls with VOIP. I don't understand what is VOIP and I need some help. I only know it's regarding internet calls. Anyhow, any reviews for this provider?
Thanks.