BlackBerry has just rolled out the latest version of BBM, making BBM Voice and BBM Channels available to iPhone and Android owners.

Through BBM Voice you can call any BBM contact for free via Wi-Fi or cellular data. Meanwhile Channels is Blackberry's sort-of-social-network that lets you "follow" topics and chat with other BBM who share that mutual interest.

The update also throws in Dropbox support to let iOS and Android users send files directly to other BBM-ers. All very handy stuff.