When it comes to sending messages to friends outside of typical SMS text messages, Facebook (NASDAQ:FB) is the 800-million-user gorilla in the room. It's acquisition of WhatsApp put it at the top of the list of messaging-app companies, especially when you combine the app's 800-million users with the 600-million users who are on Facebook's homegrown Messenger app.

There are several other popular messaging apps, including WeChat, Line, Kakao Talk, Viber, and Kik. Google (NASDAQ:GOOG) (NASDAQ:GOOGL) preinstalls its Hangouts app on most Android smartphones, but it doesn't disclose any user metrics. But one messaging app is absolutely dominating the competition, at least on Vodafone's U.K. wireless network.

Vodafone operates the region's third-largest cellular network, serving more than 19.5 million customers.  And according to Vodafone's CEO, Snapchat accounts for 75% of mobile-messaging data traffic on the company's network.

Source: Flickr/Adam Przezdziek.

Dominating the competition
Part messaging app, part social network, Snapchat's huge data usage is naturally tied to the fact that the primary communication media in Snapchat are photos and videos instead of text. Additionally, Snapchat's foray into content curation has likely had an impact on the amount of data the app's users consume each month. Nonetheless, the huge disparity in data usage between Snapchat and other messaging apps from Facebook and Google points to how big of a threat the app is to these companies that rely on time spent in their apps to grow revenue. 

It's not as if Facebook and Google don't offer their own video and photo messaging capabilities in their apps. In March, Facebook introduced Messenger Platform, which makes it easy for app developers to insert photos and videos from their apps into Messenger. Google Hangouts also includes things like stickers, the ability to insert maps, and even live video chatting.

For many, however, the preferred method for sending and consuming pictures and videos appears to be Snapchat.

Why Facebook and Google should take note
While Google and Facebook don't directly monetize their messaging apps for the most part, they do use them to collect data from users. Facebook and Google have both invested in artificial intelligence to scrape data from the texts, photos, and videos you send to your friends through their messaging services and on their other platforms.

One of the main reasons Facebook says it purchased WhatsApp is because there are very few services that will ever reach 1 billion users. (WhatsApp had 800 million monthly active users as of April.) But people spending time in WhatsApp means that they're not spending time in Facebook Messenger, which would would impact Facebook's ability to grow its average ad prices with better targeting.

Additionally, Facebook is looking for more ways to monetize the actual usage of Messenger and WhatsApp with things like payments and games. If users are using other platforms like Snapchat to send more expressive media to one another, it reduces the impact those direct monetization efforts could have on Facebook's income statement.

Moreover, Snapchat's expansion into curated content like Our Stories and Discover opened the door for the company to offer advertising spots. The company reportedly charges $20 per thousand impressions on its Discover platform, with some channels averaging as many as 2 million views per day. That's brand advertising revenue that's not going toward Facebook's expansion into video ads, or Google's YouTube platform.

With a rapidly growing user base that skews toward a younger, more valuable, demographic, Snapchat clearly represents a threat to Facebook and Google, especially as the former works to directly monetize its messaging apps. Although Vodafone only offers a small glimpse into how people are using messaging apps, the disparity in data usage bodes well for Snapchat's video-advertising business.

Those writing off Snapchat as a non-factor should take note. There's a reason both Facebook and Google tried to acquire it.