BOISE (AP) — A state fund that has helped keep telephone landlines affordable for rural Idaho residents for the past 30 years is in jeopardy as more people switch to cellphones.

The Idaho Public Utilities Commission is seeking to figure out how to keep the state fund solvent as it loses revenue that's acquired by surcharges on landline bills, the Idaho Statesman reported .

The Universal Service Fund was created under the Idaho Telecommunications Act of 1988 to ensure reasonable landline rates by subsidizing phone companies. Eight small phone companies have shared about $1.7 million annually from the state.

Over the past two decades, the number of home landlines has dropped by more than two-thirds, according to the commission. The number of business landlines has also decreased but at a slower rate.

In September, the commission doubled the surcharge amounts after the fund collected $500,000 less than it paid out during the last fiscal year. The surcharges don't apply to cellphones or internet-based phones. That would require additional authorization from the state Legislature.

The fund ended last year with a balance of $80,784, and the commission said the fund has become unstainable even with the higher surcharges.

The commission has scheduled two workshops in coming weeks to discuss the issue with industry representatives and the public, commission spokesman Matt Evans said.