How should I represent a telephone extension in multiple-language environment?

1. What is phone number and phone extension?
2. What is phone extension in application?

What is phone number and phone extension?

What Is a Phone Extension? Put simply, a phone extension is a shorter telephone number that you can assign either to an individual, to a team, or to a department. For example, you may assign #001 to your sales and marketing team or #002 to the accounts department.

What is phone extension in application?

For a residential line, an extension allows users to answer a call from anywhere in the house. It essentially means you have a second or even third instrument connected to your main number. When someone calls your phone number, all devices in the house will ring allowing you to answer the call from anywhere.