Not just locally on the device! There must be an error when calling or texting the number.
Data must work for internet for Signal, VoIP, etc.
This is for a UK PAYG SIM.
There should be no way for anyone to demand my number, or for me to leak it, or doing so should be irrelevant as it does not work.
Is this a statement, or a question?
Updated
So you are asking if this can be done? Some providers have data only Sims like what you get in a hotspot, or you could turn on do not disturb.
They don’t come with any phone number?
The one I had in my hotspot did not have a phone number attached. It was provisioned by the IMSI. This plan was cheaper than using my phone as a hotspot. I assumed that there was no phone number so you couldn’t game the system by getting this cheaper deal and popping the Sim into a phone.
I don’t think so. As providers assign a number to each subscriber, like even an Apple Watch technically has its own number.
So the issue is the “way for anyone to demand my number “
Oh. Perhaps a hotspot; and tether to it. And use WiFi wherever you can otherwise? “They” could demand your number but it couldn’t ring you.
You could try turning on Do Not Disturb for all numbers, all the time. The calls and texts will technically still happen but you won’t be notified of them. You may be able to avoid voicemails if you never set it up. You’ll see all your texts if you ever open the app although you may be able to disable or remove it. (YMMV based on your particular phone.)