Viber 2.4 beta for BlackBerry system requirements:

Free calls are available for OS5 & OS7 only. OS5 users with platform 6.x.x must
have OS 5.0.0.748 or below be able to use voice.
*Click here for instructions on how to check your OS and platform.

 - CDMA devices with OS5 will not support voice.
 - Devices with BES will not be able to use 2.4 beta until further notice.
In the meantime you can download 2.3 beta here.

The following devices have been tested with voice:

8520 9700 9810 9860 9900

The following devices have been tested with messaging, groups, stickers and emoticons.

8520 9300 9700 9780 9790 9800 9860 9900

Stay tuned for updates by visiting us on Facebook and Twitter:

http://facebook.com/viber
http://twitter.com/viber