Depends on a country, in Sweden you can move your mobile number to any telco, and anyone can look up your number and your home address using something like [0]. But yes, it is still tied to a country.

- [0] https://hitta.se

Yes, what I meant to say is that the SIM card is tied to exactly one telco at any particular time. It's also tied to one device at a time.

Perhaps one of the virtual SIM card offerings would work with Signal though.

I'm juggling too many SIM cards and phones already. I don't want any new dependencies that complicate matters further.

You only need the sim card active to activate your signal with that number. After that you don't have to be connected to a cell network at all.

But I still need to keep the SIM card active or I could never switch phones (or reinstall the phone OS) without losing my Signal identity.

I cannot ever let go of the phone number I used to activate Signal. In practice, that means I need to keep paying for a phone tariff I may no longer want.

True. I was assuming most people have at least one phone number they want to keep long term (even if it's not always active with their cell). Note though that signal will also work fine with non-traditional services that provide free or much cheaper phone numbers like google voice (US), skype, or twilio.

It is true though that you do need to maintain a phone number. That is one of the trade-offs they made to allow it to actually be usable. I have not seen a better solution for encrypted communication yet.

How does the phone number tie-in make it usable? Phone numbers and SIM cards are about the most user hostile thing I can possibly think of.

What's wrong with the way Threema does it for instance, which is essentially to bind the identity to a key pair that you can back up?

Threema appears to optionally do the exact same thing. Signal eschews the flexibility to ensure more universal usability by being able to assume that anyone who uses signal can be associated with their phone number. An assumption that holds for the vast vast majority of potential users.

I don't see how making phone numbers mandatory makes Signal easier to use at all. There must be another reason for this restriction. Some say it's for spam protection.

Signal will work with Google Voice, but as far as I can tell you still need a smartphone to use it. Without that, you can't even set up an account because you need to scan an OCR code first.

No, you can change the number associated with your Telegram account.

I was talking about Signal. Sorry I didn't make that clear. The phone number is your identity. Changing it means reregistering with a different number.

[Edit] And I think it's essentially the same with WhatsApp, only they now make it a less manual process.

Ah, I should have mentioned that I was talking about Telegram in my original comment, too. Can't edit it anymore :/