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?
They do, at least where i live (not UK, but still Europe)
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.
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.)
AFAIK this is not possible for a working number. Failed dial tone and “text message not delivered” are handled on the carrier level, if you block a number then they’ll just get a “busy” tone when calling and nothing when texting. You can’t blanket reject everything while retaining data, unless you disconnect from cellular and only use WiFi.
Yet Another Call Blocker does block all calls, that is my phone never rings, and I never see any notification of a call.
That’s doing that locally on your device, not on the carrier network. It’s definitely a good solution for this problem though.
Yeah but like I said, anyone who calls you will just hear the “busy” tone or direct to voicemail. They won’t get the “invalid number” tone like OP wants.
Don’t give people your phone number. Afaik signal now works without it.
As a downside, you may find you are not as important for these other people as you think, people are under no obligation to accept you forcing your quirks on them.
I already have everyone I need on Signal.
I am trying not to leak my data plan number to others, by for example accidentially tapping call back with the wrong SIM.
The only way is a data only SIM card.
It won’t have a phone number for anyone to call or text.
Of course you can’t make calls or texts either. You have to setup some kind of SIP service is you need to.