iPhone 11: Unknown name showing up without number? [duplicate]

Solution 1:

Since your device didn’t assign the name, it came from caller ID

Contact your carrier for details of how and why they vet those names or if they just let people feed data claiming to be whatever sender they want and easily spoof (Lie to) the caller ID system.

Your carrier and national cell phone regulator would be the people to look at if and how SMS naming is being regulated or if the carriers can do whatever they please in terms of naming and whether you get to know who sent that SMS.

Solution 2:

I receive messages from BX-ZZZZZ where ZZZ is my bank's abbreviation. So some services can message under alphabets too. They need to get registered somewhere.

Searching, I stumbled upon https://www.fast2sms.com/help/sender-id-create/ which claims to register you for a time period during which all your SMSs will be sent under your custom business abbreviation.