VoiceOverIP

Voice-Over-Internet Protocol

How Stuff Works - VoIP

Voice over IP calculator

Internet2 (!) Voice over IP Working Group

Wikipedia:Voice over IP

sipgate.de german VoIP provider

---

VoiceOverIP / Wi-fi mobile phone:

VoIP "Handy" - wirbt mit "in offenen WLANs telefonieren"


 * http://www.sipgate.de/catalog/product_info.php?products_id=28