IMO he is spoofing numbers so he can set anything as a call ID anyway.
I was called by spoofers for a few weeks (same exact time every day but with a different number). My (European) provider said they can’t do anything about it.
Truthfully nobody is safe on our current phone system.
Even though this is not probably what is happening to OP and I don’t want to overly worry them but checkout this video by Veritasium :
youtu.be/wVyu7NB7W6Y?si=HG6zC6YnXsjqt89-
Maybe OP should change completely of phone number.
Moonrise2473@feddit.it 1 week ago
Trivial for law enforcement, almost impossible for regular people
AllNewTypeFace@leminal.space 1 week ago
Depends if you’re in a country where ID has to be shown and registered in a database when activating a SIM card.
nokturne213@sopuli.xyz 1 week ago
It is likely a voip that is being used.
Moonrise2473@feddit.it 1 week ago
for some reason telecoms worldwide are allowing voip companies to spoof almost any number - you can ID them but require cooperation of too many companies for a single individual without a court warrant