Is it necessary to search each time if the 3 digit number is an area code?

No pattern; you have the “decoder ring” with phone lookup.

If you look at the directory you linked, you’ll see that no area code begins with 0 or 1.
Also, no area code ends with 11.

Hence, 000–199 are not area codes. Neither 211, 311, 411, 511, 611, 711, 811, nor 911 are area codes. Also, 555 is not an area coed. ;-p

AFAIK, any other 3-digit number can be, but might not yet be, an area code.

When the phone companies started requiring you to dial 1—### – ### – #### they made it so there could be a lot more area codes. Before that, the second digit for an area code was always a 1 or a 0; that was how you could tell it was a long distance call.

My cell phone requires 10 digits even for local calls, I always have to “dial: (key in) an area code. With number portability, area codes are no longer tied to a geographic area. My girlfriend’s phone number is in area code 847, which is northeastern Illinois, but she has lived in California for five years, and before that lived in Colorado for nine years. She hasn’t lived in Illinois since 2006.

My cell provider has started requiring I use the area code, even for local calls. Not sure why. If I had the decoder ring I could find out.

I just know someone said just by glancing at a lot of numbers and said “Those are not area codes, and the “phone numbers” “spams” as the person called it, were varied not just end in 11 or not before 199.

@flo If a person gives you a phone number like, 123–456-1234, you know the 123 is the area code.