WengoPhone is a Voice over IP application based on standard protocols like SIP and RTP. It is also not easy to use as a provider-agnostic SIP client. It enables voice, video and text chat between two clients. Features include a contact list with presence and status, call history and NAT traversal capability.
In conjunction with commercial services provided from Wengo (http://www.wengo.fr
), WengoPhone can be used to call regular PSTN lines and/or send SMS messages to cell phones.
Interface: Graphical (Qt)