compatible SIP-based VoIP services.

Xten says its Voice over IP (VoIP) and Video over IP SIP (Session Initiation Protocol) softphones are carrier-grade IP telephony SIP endpoints, "delivering the quality of service and features that large providers require to serve their customer base."

The company offers a free SIP softphone dubbed X-Lite, in addition to the "fully featured" X-Pro commercial softphone. Xten's softphones are said to be fully RFC3261 (SIP), RTP/RTCP (RFC 1889) and SDP (RFC 3264) compliant. They are compatible with the full range of Windows operating systems including Windows CE and Pocket PC, as well as Mac OS X.

Earthlink's free online calling service is available here.

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