You aren't, really. You are receiving calls from someone who has "accidentally" configured their corporate telephone system to send bogus Caller ID data. Unfortunately, it's very easy to do, and there's no penalty even if they get caught.
The 874 area code is an invalid unassigned number. If you are getting calls from this area code they are being "spoofed".
It's a series of area code digits that are not yet in use. In the UK, 118 is Reading but 119 is unassigned. In the US, 212 is New York but 211 is unassigned.
761 is an unassigned area code reserved for Palm Beach County, FL.It is an unassigned area code currently reserved for Palm Beach County, FL.
Area code 558 is unassigned in North America (USA, Canada, etc.). International country code +55 is Brazil.
According to NANPA, area code 748 is currently unassigned. It is not a valid area code.
The area code 459 is actually located in Mexico. However, if you are receiving phone calls from a number with this area code, most likely it is some type of scam.
The area code "258" is currently an unassigned area code. The closest area code to area code "258", is area code "260", which is assigned to the state of Indiana.
At current the area code 997 is unassigned area code and is not fixed to a city or state, if one receives calls from such number, it is most likely a telemarketer that is spoofing the the phone number, making it appear that they are someone else so the call is not blocked.
As of this writing, area code +1 463 is unassigned. Country code +46 is Sweden.
Area code 429 is an unassigned code in the United States. Most likely a spoofed area code in which a spammer is hiding behind to protect agencies from finding them. If you do not recognize a phone number when it calls, then just don't answer it. Answering unsolicited calls only confirms that your number is a valid/active number and then that information is passed along to other spammers who will also start calling you, too.
Country code +969 is currently unassigned.
In North America (country code +1; USA, Canada, etc.), area code 454 is unassigned. Country code +45 is Denmark.