Facebook and Apple are getting a run for their money, thanks to the growing popularity of texting apps like Line and WhatsApp. 

Though they're used on mobile devices, reports Wall Street Journal, neither company receives any revenue from them, and for Facebook in particular, the more time spent on the apps means less time spent on its site.  

The messaging apps pose a similar problem for wireless carriers as well. As The Journal points out, these companies have been relying on the services for years for "the bulk of their revenue," but the rise of the texting apps took away $23 billion by the end of last year, according to market research firm Ovum.  

At first blush, consumers might think they're saving money by using these apps, but if the trend continues, which it likely will, then wireless carriers might try to make up for lost revenue by hitting customers with higher usage fees. 

[via WSJ]