Beginning June 1, consumers dialing a phone number with the 512 area code must include the area code when dialing the number.

The mandatory 10-digit dialing is in preparation for a new overlay area code that phone companies can start issuing July 1.

The Public Utility Commission of Texas approved the implementation plan June 28, 2012, to add the 737 area code to the area served by 512, which includes portions of Bastrop, Burnet, Cadlwell, Hays, Lampasas, Milam, Travis and Williamson counties. The new area code was added because the utility will run out of 512 numbers.

Areas with the new 737 area code will start being issued July 1. PUC of Texas spokesman Terry Hadley said the mandatory 10-digit dialing and issuance of the new area code are staggered to ensure there are no issues with the 10-digit dialing.

He said that more than a decade ago, many new area codes were being added throughout the nation, and a number pooling program was made available to ensure that all numbers in a particular area code were being used and not being hoarded by phone companies.

Hadley said this allowed the PUC of Texas to have just one area code in the 512 region for a longer period of time.

He said the main concern with requiring 10-digit dialing is that a small pool of consumers who only have a landline and no cell phone or computer might not know about having to dial the 512 area code. He said it is important for others to inform people who fit in that category.

If a consumer forgets to dial 512 before the phone number, the consumer will hear a fast busy signal and the call will not connect.

Consumers may still dial 911 and 411 with just three digits. For more information, download the PUC of Texas' PDF here.