Beeper is a single app that seamlessly integrates 15 external messaging applications in sync with one inbox. With a clean standard interface, instant search across all chat networks, and unified with filters. It uses an Open Source Protocol and is available to run Beeper's backend using an individual's server or pay for their hosted option. 

This is an ideal messaging app for a business that operates several social media accounts; with a small worth it fee for USD10.00 a month subscription fee, you'll be able to manage all your social media platforms in just one app. Beeper connects to the following Messaging apps: Whatsapp, Facebook Messenger, iMessage, Android Messages (SMS), Telegram, Twitter, Slack, Hangouts, Instagram, Skype, IRC, Matrix, Discord, Signal, and Beeper network. You can check out for more info on this.