Will the U.S. Ever Run Out of Telephone Numbers?

Phone numbers as we know them may soon be endangered. While there are billions of potential digit combinations, it’s not an infinite number. Eventually, it’s possible that we will have used up every available phone number. Prior to the 1960s, the telephone system used something called the 2L-5N format, meaning 2 letters and 5 numbers. An example is the telephone number Lucy and Ricky Ricardo used on the TV series I Love Lucy. Their phone number was MU5-9975, the MU indicating their Murray Hill neighborhood. It wasn’t long before the system became an “all number" system, ditching the letters. So, what will happen when the numbers run out? It has been proposed to add more digits because adding one digit to the area code and one to the dialing prefix would create an additional 640 billion possible numbers. However, that would be easier said that done. Everything formatted for a 10-digit number would have to be altered to work with the two extra digits. Others believe that by the time the 10-digit numbers near total exhaustion, the world will have transitioned away from telephony and toward Internet-based calling.