I've used an iPhone for a long, long time. Part of me always cringes when I see the "green text bubble" pop up on my phone. Why? It means it was sent in the clear using a protocol that was invented in the 1980s. I'm also not a fan of routing all of my messages through Facebook, WhatsApp, or any of the infinite number of chat clients where targeted advertising is the main driver.
Enter Signal: the free, open-source, encrypted, and cross-platform messaging client that you should be using.
"An encrypted chat client? That sounds really complicated."
Let me preface this by saying that I can barely add and subtract on a good day. Math is definitely not my strong point and part of the reason that I ended up with a degree in psychology. That being said, Signal is dead-simple to use and completely abstracts the "fully encrypted" component of the client. You don't need to send PGP keys, configure certificates from the OpenSSL command line, or set up any type of encryption gateway. Signal is incredibly easy to use and just works. The only requirement is that you need a phone number: I don't have a problem using my own, but there's nothing stopping you from using a Google Voice number instead.
There are really two components: the mobile client and the desktop client. Signal is a "mobile first" client, meaning you need to have it installed on your phone before you can set up a desktop client. The desktop client then sync with the phone install. After the phone install, you enable access to your contacts and it'll notify you of other users in your contact list that have Signal installed.
As mentioned above, one of the best features of Signal is that it's completely cross-platform. Android, iOS, Mac, Linux, and Windows all have the same user experience. This is also a major reason that I ended up going with Signal: my team is a mix of iOS and Android. This way everyone gets the same level of encryption, and I don't need to worry about data being sent in the clear.
Voice and Video Chat
Another outstanding feature of Signal is voice and video chat. Why? It's all encrypted end-to-end and works extremely well. I've got spotty reception in my office which means there's a high likelihood of calls being dropped. On top of that, I've had awful luck with Verizon WiFi calling. Even though I've got a solid Internet connection, the WiFi call eventually gets dropped or someone ends up sounding like a robot. I haven't encountered the issue with Signal: both audio and video calls are crystal clear. In fact, the audio quality is far better than what I'd find with a normal phone call.
Signal recently added decentralized group chat management. Prior to that, it was a bit of a pain point when you had a team chat going: nobody could be kicked from the channel and instead they'd need to voluntarily leave. However, that's been addressed in the recent releases. You can add people, remove people, designate administrators of the channel, etc. It works extremely well and could easily replace something like Teams and WhatsApp for a communication channel.
It's well worth your time to give Signal a try. It's free, easy to use, and only takes a minute to set up. Most people are surprised when they see how many of their existing contacts already use Signal. It also has the majority of features that you'd find in the more "mainstream" chat clients, minus the advertisements that go along with it. You can also take comfort in knowing that if anyone were to tap your phone line or spy on your instant messages, it'd cause someone to say "damn it, they must be using military-grade industrial encryption firewalls" just like in the movies.