NEW AREA CODE FOR NEW MEXICO COMING! On October 7, 2007 - the state of New Mexico will be split into two area codes. The northwest region of the state will retain it's current area code (505) and the rest of the state will get a new area code (575). This change will affect wireline and wireless services as well as other communications services. Why? We are running out of usable telephone numbers due to growth in state residents, communications service providers, available products, and additional lines, so the state needs to add a new area code to meet demand.