Dialing an extension on an iPhone is necessary when you need to contact a specific person or department within a company or organization. An extension is an additional number that is added to a main phone number to reach a specific destination. For example, if the main phone number for a company is 555-1212, and you need to reach the sales department, the extension might be 1234.
There are two ways to dial an extension on an iPhone. The first method works if you are calling from the Phone app: