Facebook said it will start using Messenger's messaging service in its Instagram photo and video sharing app, which is the first major step in its plan to link messages across its suite of apps.
This step allows users of each service to find video calls to contacts on the other end, send messages to them, and stop them without having to download both applications.
It also offers features, such as custom emojis and themes that were the mainstay of Messenger, but was not previously available in Instagram's simple messaging service, and it will also introduce new features, such as hidden messages.
If users agree to the update, the Instagram messaging icon will change to the Messenger logo, and as with Messenger, Instagram users who were not able to forward messages will be able to do so with a maximum of 5 people at a time.
"The goal of this exercise is to get to the point where we build something once, and then it works across all applications, so we don't have to repeat the same thing multiple times," said Stan Chudnovsky, president of Messenger.
The initial launch of the service began yesterday, Wednesday, in a few countries, and will soon expand and launch internationally.
And Facebook CEO Mark Zuckerberg first announced his vision to integrate messaging through apps early last year.
Ultimately, the company aims to integrate WhatsApp with Messenger and Instagram, and to extend full encryption across the three services.
The move is likely to appear in antitrust deliberations over the Facebook acquisition of Instagram and WhatsApp, which has been the subject of numerous investigations.
Antitrust experts have raised concerns that merging services together could make it difficult for regulators to dismantle the company.
"No new categories of user data will be switched between Instagram and Messenger, except for what has already been shared, as the two messaging services have relied on the same back-end infrastructure for years," Chudnovsky said.