HALLOWELL, Maine (AP) Utility regulators in Maine are opening an investigation into the numbering practices of wireless giant T-Mobile as the state runs out of available phone numbers within its sole area code.

The Maine Public Utilities Commission has said the 207 area code is predicted to run out in the final quarter of 2025. Commission Chair Philip Bartlett said Wednesday the T-Mobile investigation is part of the state’s effort to extend the life of the area code as long as possible.

The commission said in a statement that it has questions about T-Mobile’s forecasting process for numbering resources. It also said it wants to know more about the rate at which old numbers are returned to the system.

T-Mobile did not immediately respond to a request for comment.

The commission said it has called on T-Mobile to provide information such as an explanation of how the company forecasts growth in Maine. It said it also wants to know why T-Mobile is using a high number of special numbering categories, which the commission said might unnecessarily increase the need for more numbers to be taken from the 207 numbering pool.