(Read more: Zuckerberg says WhatsApp is worth more than $19 billion)
"Based on some recent communication company sales, from Viber to WhatsApp, and applying the same dollar-per-user calculation, [BlackBerry] is worth between $650 million and $3.4 billion," said CNET Senior Editor Dan Ackerman.
BBM has an estimated 85 million monthly active users, while WhatsApp has more than 450 million.
(Read more: Did investors miss the message on the value of BlackBerry's BBM?)
Separately at the Mobile World Congress, BlackBerry unveiled its Q20 mobile phone, a throwback to some of its older models with a QWERTY keypad and trackpad.
While it makes sense for BlackBerry to focus on what's worked well, it's not likely to be enough to save the company, according to Ackerman.
"Even if the Q20 is a great [BlackBerry] phone, in the way that the Q10 wasn't, it's still fighting a losing fight long term," he said.
As workers increasingly use their personal smartphones for work instead of having a separate phone, Ackerman said, the need for an additional BlackBerry device could be dwindling.
—By CNBC's Althea Chang