Please have a look at the following sites, micro-blogging done right: GNU/Social is a special software that allows for decentralised twitter-like micro-blogging. The following sites use software like this to allow its users to be able to socialize with anyone from any GNU/Social server.
Join https://p2px.me for free instant messaging with no crap, no spam, and ease of use.
New free service for everyone at https://p2px.me! A peer-to-peer enthusiast website with GNUSocial as the server software for social networking and XMPP for instant messaging!
The following is more of where to get apps for your phone and how to configure them.
Install the application and use the following configuration when connecting with those apps:
Username: firstname.lastname@example.org (Some client's the username will only be 'username' no @p2px.me)
If asked to confirm a security certificate, please be sure to confirm the following details: Certificate is for the domain 'p2px.me'. SHA256 fingerprint is 4A:8D:EE:7B:A0:38:14:F9:D1:AB:77:69:3D:E6:05:AC:09:4F:3E:65:B7:BE:EB:3B:3B:B5:F8:5F:DB:5E:EB:FA. It was also issued by Let's Encrypt X3.