The separation between Facebook, WhatsApp, and Instagram is about to get even blurrier.

Speaking during the company's quarterly earnings call, Zuckerberg confirmed that Facebook wants to make it easier to send messages across its apps, but cautioned that it would be a "a 2020 thing or beyond."

"We're really early in thinking through this. There's a lot more we need to figure out before we finalize the plan," Zuckerberg said.

Still, the CEO offered an explanation of why the company wants to merge the apps' underlying infrastructure.

"The first reason I'm excited is moving more to end to end encryption by default in our products. People like this in WhatsApp. I think it's the direction we should be going in. I think there's an opportunity ... to have encryption work in a consistent way across the things that we're doing."

Zuckerberg says there are "tens of millions.. maybe more but I'll go with that" of Android users who use Facebook Messenger as their default SMS app $FB — Karissa Bell (@karissabe) January 30, 2019

Zuckerberg also noted that there would be practical benefits to allowing people to send messages between apps. In countries where WhatsApp is dominant, for example, being able to message a Facebook Marketplace seller via WhatsApp instead of Messenger might be more convenient. He also said the "tens of millions" Android users who currently use Messenger as their default SMS app would benefit from having encryption enabled as a default.

The CEO didn't share any thoughts on how such a plan would benefit Instagram.

News of Facebook's plan to merge the back-end infrastructure behind all its messaging apps has raised a number of questions about privacy. It's also just the latest sign that Zuckerberg is tightening his control over the services, which he and initially promised independence from Facebook, as Facebook depends on Instagram and WhatsApp more for future growth.