This is very useful when dialing a phone number with an automated answering system. That pause will let the main number dial, wait a moment, and then dial the extension so you don't have to.

How to Use Google Voice to Dial a Number With an Extension. Google Voice lets you or your employees dial any phone number from a phone or Google Talk client, including business phone numbers that ...

Automatically dial extensions for Android contacts Instead of dialing the extension for people or businesses you call often, program them right into the contact information.

Having friends with an office job in the typical corporate environment often times means having to dial a desk phone with an extension. As Lifehacker points out, this usually results in having to ...

Install Dial Congress, an extension for the Google Chrome browser that turns news stories, Wikipedia pages, and Google searches into a congressional phone directory.