WhatsApp just became the first messaging app to clear the billion-user mark, meaning its user base has more than doubled since Facebook bought it back in 2014.
Facebook Messenger itself isn’t doing too shabbily, with 800 million monthly active users. Just shy of 1.6 billion people use the core social network each month, too, with more than 1.4 billion using it on mobile.
“There are only a few services that connect more than a billion people,” Mark Zuckerberg wrote in a Facebook post. He also reiterated what WhatsApp said when it dropped its annual fee last month, that the next step is to “make it easier to communicate with businesses.”
Get Data Sheet, Fortune’s technology newsletter.
As leaked screenshots recently suggested, WhatsApp users might also soon be encouraged to share their account data with Facebook — a move that would give the social network even more valuable information for targeting ads.
Outside of Planet Facebook, the next-biggest powerhouse is China’s Tencent, which also has dual messaging services. As of November, Tencent’s Wechat had 650 million users, while the number of people using its older QQ messaging service on “smart devices” was 639 million. And since we’re comparing, Tencent said in those Q3 2015 results that its Qzone social network had 577 million monthly active users on smart devices.
What do these sky-high mobile messaging figures mean for traditional telcos? Andreessen Horowitz VC Benedict Evans put it well: