BlackBerry is rolling out an updated version of its Messenger application -BBM 7 which was originally launched for BlackBerry 6 or higher OS handsets in December, the update is extending voice-calling capabilities to older devices running BlackBerry OS 5.

BBM version 7 offers BlackBerry Messenger users free voice calls via its BBM Voice function, allowing users to make calls over a Wi-Fi connection. A split-screen feature allows toggling between messaging and voice options, and users may also talk and text at the same time, enhancing business collaboration possibilities. The BBM platform identifies which contacts are available for voice conversations, and in the event the call recipient is not free to chat, they can respond to the caller via text.

Blackberry OS 5 may well be an old OS now, but I still see so many people around talking and texting on their BlackBerry Curve 8520 and Blackberry 9630 and few others still running on OS5.

http://www.wasconet.com/blackberry-messenger-7-with-bbm-voice-call-on-os-5/