There’s a meme that every person has a U.S. government agent assigned to read their text messages. That’s not true. But government agencies, from the National Security Administration to local police departments, can potentially read the conversations on many text messaging applications. Fortunately, this is not always the case, and there are many ways you can protect your privacy.
Can they? Absolutely. Do they? Most likely not. Wide surveillance checks key words and phrases, filters them and might trigger a closer check by another machine. Other than that, if the government is checking on your messages, they’re already checking on you specifically for a reason. There is no encryption that’s going to stop that, they’ll read it before it’s encrypted.
Not if you’re self-hosting and de-googled they won’t.
You can’t self host SMS or telephony voice. All of your clients contain proprietary code and zero days that could easily be exploited by a state actor.
If you ever go completely radio silent, then you’re more likely to be manually investigated as you are a statistical anomaly to the mass surveillance algorithms.
I meant self hosting XMPP or similar to replace texting with.
If they wanted to, they could. They’ve got backdoors built into everything, including processors.