One area where current BlackBerry OS Java developers have long struggled with is true VoIP communications. That is the reason I was very happy when Tru decided to share some of the details of how they ported their VoIP app to BlackBerry 10. They have been documenting some of the steps on their blog but they recently shared some more info in a Q&A on the BlackBerry DevBlog.
Tru details how much easier it has become to bring software to the BlackBerry PlayBook now that it is standards compliant by “building on the shoulders of giants.” in short that means making use of the wealth of open source libraries and software stacks built for Linux and similar POSIX systems. They used the opensource PJSIP multimedia stack to bring Truphone to BlackBerry 10 using its audio, video, presence, and IM capabilities.
If you are a dev I recommend checking out the full Q&A on the DevBlog