Many businesses and offices have extensions that allow you to reach a specific person after calling the business's main line. This is so that businesses wouldn't have to purchase several hundred phone numbers for each person. These extensions work on any phone that calls the main business, even if the calling phone is a cellular phone.
Dial the phone number you wish to call.
Press the "#" or "*" key, depending on the way that extensions are handled in the place you are calling. (Some areas do not require these keys. If the place you are calling does not, skip this step.)
Enter the extension of the person you wish to contact at the prompt.
Press the "#" or "*" key if prompted to do so.
Do not enter the extension number before the call is connected.