VeriSign introduced a Push-To-Talk Service for mobile operators in North America and Latin America. The VeriSign Push-To-Talk Service combines a portable handset client with VoIP and SIP technologies to deliver push-to-talk voice services over any standard wireless packet data infrastructure. The Push-to-Talk Service enables subscribers to place private and group calls across one or more service provider networks at the touch of a button.
This service is currently available for evaluation by carriers who support CDMA networks in the US and certain countries in Latin America.
http://www.verisign.com/
