But BlackBerry isn’t going down without a fight. In fact, the battered Canadian company — which lost $5.9 billion last year — believes that BBM can help it claw its way back to profitability. At the same time, enterprise-focused mobile-messaging apps are flooding the market, undoubtedly aftershocks from WhatsApp’s staggering payday and sudden, heightened interest among investors.

For BlackBerry’s part, the company is trying to extend BBM’s reach. First, the phonemaker made the messaging app available to users of Apple’s iPhone and devices that run on Google’s Android operating system (and soon, Microsoft’s Windows Phone). Chief executive John Chen also announced that he would consider bringing BBM to desktops so that people can converse across screens. And this summer, BlackBerry will launch the eBBM Suite, a corporate-grade, encrypted version of the service that the company hopes will help it return to its enterprise roots. “I feel like we have a good head start,” says Thad White, director of BlackBerry’s BBM for business division.

Meanwhile, Microsoft, Cisco, and other companies that cater to corporate customers continue to develop their collaboration tools into made-for-mobile applications. Smaller players like TigerText, which provides a secure-messaging platform for health care professionals, and Cotap, a recently launched enterprise-focused texting service, are also nipping at BlackBerry’s heels. One advantage to the new alternatives? Corporate customers don’t need to pay for a server or any other kind of back-end hardware to manage them. “The number of enterprises doing that is diminishing,” says Jim Patterson, co-founder and CEO of Cotap.

The competition on the consumer side is even fiercer. In addition to WhatsApp, there are a growing number of lightweight messaging services such as Tango and WeChat, which is popular in China. These are cheap and have long worked across operating systems, unlike that of BlackBerry, which waited until late last year to open BBM’s walled garden.

Why are messaging apps so hot? Because they are fast becoming people’s preferred mode of communication, with astonishing engagement stats to match. (In April, WhatsApp’s global users sent 64 billion messages in one day.) Where there are eyeballs, there are potential revenue opportunities, from subscriptions to transaction fees to product sales.

That opportunity is not lost on BlackBerry, which believes it is uniquely positioned to bridge the gap between the enterprise and consumer worlds with a single, secure app that lets people chat with friends, family, and co-workers alike. Though the company’s North American nosedive could affect its ability to get people interested in using a BlackBerry product again, one thing is clear: The business opportunity around messaging apps is no matter to LOL about.

This story is from the April 28, 2014 issue of Fortune.