What does ext. mean when a website asks for ur phone number?

Question

is it the first 3 digits or what??

Answer 1

Extension

Typically, extensions exist in business phone systems. The business has one phone number and each employee has his/her own extension.

Where I work, my extension is 103. So if the phone number for my business is [phone], then to get me you would dial [phone] and request extension 103.