This is a device allowing a user to make VoIP calls using session initiation protocol (SIP). SIP is a telecommunication technology developed as a fast, easy standard for delivering IP-based data, voice, and video communications.
AT&T Inc. is a premier communications holding company in the United States and worldwide. Operating globally under the AT&T brand, AT&T is recognized as the leading worldwide provider of IP-based communications services to businesses and the leading U.S.
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