SIPphone: www.sipphone.com [1]
Skype: www.skype.com [2]
SIP Broker: www.sipbroker.com [3]
Google Talk: www.google.com/talk [4]
Vonage: www.vonage.com [5]
Lingo: www.lingo.com [6]
Total Talk: www.totaltalk.com [7]
Asterisk: www.asterisk.org [8]
SIPfoundry: www.sipfoundry.org [9]
GnomeMeeting.org: www.gnomemeeting.org [10]
Damien Sandras' GnomeMeeting Blog: blog.gnomemeeting.net [11]
KPhone: www.wirlab.net/kphone [12]
CounterPath: www.xten.net [13]
Links:
[1] http://www.sipphone.com
[2] http://www.skype.com
[3] http://www.sipbroker.com
[4] http://www.google.com/talk
[5] http://www.vonage.com
[6] http://www.lingo.com
[7] http://www.totaltalk.com
[8] http://www.asterisk.org
[9] http://www.sipfoundry.org
[10] http://www.gnomemeeting.org
[11] http://blog.gnomemeeting.net
[12] http://www.wirlab.net/kphone
[13] http://www.xten.net