BlackBerry has opened up its BBM apps for iPhone and Android, allowing anybody to sign in instead of having to join a waiting list.

"Users can now immediately download, sign in and start using BBM without having to wait," it said in an email sent to Pocket-lint.

Additionally, the company has revealed that the app has helped add 20 million new active users in its first week. That means that the BBM community now stands at 80 million monthly active users across all devices.

Read: Hands-on: BBM for iPhone review

The iPhone app is available in 107 countries, while the Android app is available in 35, and BlackBerry names Canada, the US, UK, Indonesia and much of the Middle East as key markets for their adoption.

"It is great to see so many people downloading BBM, but the true measurement for us is engagement - the connections being made and the conversations in which our BBM community engages," said Andrew Bocking, executive vice-president of BBM at BlackBerry. "The power of BBM has always been the active, real conversations and interaction that our customers enjoy.

"From here on out, we will focus on active users of BBM and will no longer focus on simple download numbers."

Read: BBM takes on WhatsApp: Should you switch?