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.
I think they still have an associated number, just that it can’t be used for voice or sms (it may have changed, but the number was effectively the equivalent of an IP address in the telco system - it’s what all the switching relies on to route). They probably just don’t provision voice or sms for it.