What is the difference between an extension, a line, and a phone number?
People sometimes ask us what is the difference between an extension, a line, and a phone number. Here you will find an explanation of the difference between the three.
Extensions
An Extension is a unique login or identifier that enables you to receive or make calls when used on telephony devices such as IP Phones (e.g. Yealink) and Softphones (e.g. NCH Express Talk). The benefit of having extensions is that it allows you to make multiple simultaneous calls in your office without each phone requiring a separate outside line or additional physical lines. Using extensions, calls between employees who are working in different offices do not use up the credit on your account.
Lines
Each extension is configured with one or more lines, which are forwarding numbers for routing incoming calls. Other extension types do not have forwarding numbers associated with them. For example, an auto attendant can transfer an incoming call to a particular user, which then connects to a forwarding line or voicemail.
Phone Numbers
Phone Numbers are also called Direct Inward Dial (DID) Numbers. Using DID, you can get phone numbers without requiring a physical line. Calls come into your account via your phone numbers, which may be a toll-free or local. Your phone numbers are associated with extensions in your account so that incoming calls connect directly to a local landline. Your phone numbers are associated with your account and can either be connected to your extension, a voicemail, an external number or an auto attendant.
