I’d like to be able to chat from an Android phone without a SIM card.
Edit: Since several people have mentioned it, I’m including this note at the top. There are security issues with using a temporary number to register even if it is not needed to maintain the account. Anyone can gain access to the number and use it for account recovery, etc. I’m not an infosec person at all, but this seems pretty obviously bad. Some services will work fine with a landline or other permanent phone number, as long as you retain private access to the number.
Edit 2: SimpleX turned out to be a good fit for me. It was fast and easy to set up, and simple for my family to use. I also like that it is self hostable if I need to set that up in the future. There are some excellent suggestions and useful discussions below, and I appreciate the help. I’ll come back to this thread in the future if I need to switch
I don’t know how private/secure it really is, but Teleguard doesn’t require a phone number.
I’d really like to see some research into them, though, to know how good/bad it is.
I don’t know where to even start.
Alternative: XMPP has been around for 25+ years, can be self-hosted, there’s numerous solutions available.