Textopolis

Textopolis is a city within humans' smartphones containing messaging apps. This will serve as The Emoji Movie's setting where a majority of the main characters reside.

Description
Hidden within the messaging app is Textopolis, a bustling city where all the emojis live and work, hoping to be  selected by the phone's user.

When someone is texting, no one knows if the user will choose them, they go to a room where emojis are on a small space. Workers tell the user's selected emoji, then that emoji needs to prepare for the scan. After the emoji has been scanned it will be sent.