You may be able to create your own dumbphone by flashing something like PostmarketOS to a compatible second hand phone combined with a custom Signal client. Just apk remove the browser and any other utilities you don't need and even the librem phone might be fast enough for your use case.
They don't encourage it but they don't ban it either. Non-official clients absolutely exist for the network, some of which use signald, a backend service and abstraction layer for the signal protocol which is neither unstable nor a hack:
https://github.com/LibreSignal/LibreSignal/issues/37#issueco...
It is true that Whisper Systems runs the network and can gatekeep it as they see fit.
But your claim that Signal, as a matter of course, bans unofficial clients is objectively not true.
Additionally, they're more or less required to go after trademark violations if they get too big.
In that talk he explains why they don't decentralize their protocol or the ecosystem.
His concern is that a decentralized ecosystem means actively supporting third party implementations and having to achieve consensus when making changes, which slows down (or flat out stops) their ability to evolve the protocol and turn out new features.
That's a totally orthogonal issue to banning unofficial, unsupported clients.
> Additionally, they're more or less required to go after trademark violations if they get too big.
That's a trivial problem to solve: don't put Signal in your client name.
It's not orthogonal at all, and he's talked at length about how he views every client connected to their servers as under his control, and his dislike for unofficial clients, and his willingness to squash them if they get too big.
Before signal he was head of security at Twitter which has a similar 'squash unofficial clients if they get too big' policy.
> That's a trivial problem to solve: don't put Signal in your client name.
Signald has signal in it's client name.
Moxie and Signal didn't do anything other than asking LibreSignal politely to stop using their servers. They didn't "shut down" anything, and they have shown no interest in shutting down signal-cli/signald.
MobileCoin, the cryptocurrency that Signal incorporates and essentially sanctions, uses signald for their bot[0].
the Signal Matrix bridge has hundreds if not thousands of open source users, plus Element One and Beeper users, all using signald and not having any repercussions for years. The only 3rd party Signal client that's caught any flak from Signal that I'm aware of is LibreSignal.
also see: last time this came up[1]
[0] https://github.com/mobilecoinofficial/mobot/blob/dev/RUN.md
1. https://www.theregister.com/2022/01/11/signal_ceo_moxie_marl...
No unofficial clients + us-based? Smells fishy.
I’d rather run Telegram and/or Matrix (ideally Matrix).
Ongoing work is being done to enable Signal accounts without requiring a phone number (there's been a number of changes to the protocol to support this in the last 6-12 months), it's just not done yet.
[1] Threema
But yeah, I agree. We need a feature phone with IM support. That would be perfect.
Since they don't implement apps, there's no way to get a secure messaging system in there as SMS will be you only option. I suppose you could set up OTR or PGP, but you'd still have no built-in ability to encrypt and decrypt.
There's also KaiOS which is running on phones marketted as feature phones, although it's a fork of FirefoxOS which is Android base plus an HTML+js app model (or something).