HOBBS — The grace period is expiring Sunday in parts of New Mexico where telephone customers are making the switch to the new 575 area code. Cell phone customers who have not made the switch may find themselves out of service.

"The phone won't register at all if they fail to switch," said Jenny Weaver, spokeswoman for Verizon Wireless. "It is critical (that) people get their phones switched over."

Alltell spokesman Scott Morris said the company has been contacting customers for the past year, reminding them to make the 575 switch on their phones.

Wireless customers should contact their provider for information on how to switch their cell phones to the 575 area code.

State Public Regulations Commission spokesman Paul Carbajal said landline customers in New Mexico will receive a recording reminding them to dial 575 if they used 505 to reach a number that was moved to the new area code.

"We are doing everything we can to make this transition as smooth as possible for the consumer," Carbajal said.

Out-of-state customers calling into New Mexico will not get a recording, making it important to update communication lists, business cards and letterheads.

Carbajal said landline or cellular telephone customers who experience problems after Sunday can contact the PRC for assistance at 888-427-5772.

"If there are any problems, please don't hesitate to give us a call," he said.

The commission will contact phone companies to solve consumer issues. Carbajal said providers that fail to make network changes for the new area code can be fined as much as $10,000 daily for each affected customer.