Viber

Acquired by Rakuten
on February 14, 2014
VoIP
$900m

Gizmofive

Acquired by Google
on November 9, 2009
VoIP
$30m

SightSpeed

Acquired by Logitech
on November 1, 2008
VoIP
$30m

Teleo

Acquired by Microsoft
on August 30, 2005
VoIP
Undisclosed