The strong performance of BlackBerry Messenger (BBM) on Android and iOS continued, as it reached 20 million downloads in its first week of availability for the platforms.

However, BlackBerry is now looking to measure user engagement, such as conversations and connections being made on the service, according to Andrew Bocking, executive VP of BBM.

“From here on out, we will focus on active users of BBM and will no longer focus on simple download numbers,” he said.

BBM now has more than 80 million monthly active users, including those using it on BlackBerry devices.

BlackBerry previously said the messaging app was downloaded 10 million times during its first 24 hours of availability. Such was the popularity that many users had to wait for the app to be activated once they downloaded it.

This additional step was removed over the weekend.

During the first week of availability for Android and iOS, BBM was the top overall free app on Google Play in 35 countries and on Apple’s App Store in 107 countries. It performed particularly strongly in Canada, the US, UK, Indonesia and the Middle East.

Andrew Bocking, executive VP of BBM at BlackBerry, said on Canadian radio last week that BBM will remain a free service for the foreseeable future. BlackBerry will monetise the service through advertising and forthcoming features such as social networking service BBM Channels, he added.

BlackBerry plans to introduce video calling and voice calling to Android and iOS in the coming months, along with BBM Channels.

The launch of the app was botched in September after one million Android users downloaded an unreleased version of BBM from file-sharing sites, creating issues for the official client.

With BlackBerry in the midst of a strategic review which could potentially see it broken up or acquired, there have previously been reports that a spin-out of the BBM unit is a possibility.