AT&T can’t pull the plug on landline service for customers across California. In a ruling on Thursday, the California Public Utilities Commission (CPUC) rejected AT&T’s request to release it from its obligations as a Carrier of Last Resort (COLR), as reported earlier by Ars Technica and CBS News.

AT&T has had a COLR designation in California since 1996, which ensures everyone in the state has access to affordable and reliable telephone service. Some people in California — especially those who live in remote areas — have come to rely on their landline service, as it allows them to make emergency calls even when the power is out or cellular service isn’t available.

Earlier this year, AT&T asked CPUC to be released from its duties as a designated carrier, citing the wide availability of mobile service and VoIP. In its request, AT&T argues the “economic justification” for COLR no longer exists because alternative voice services with “reasonable rates” and “based on superior technologies” are available throughout the state. The company adds that it “bears substantial cost to maintain and operate” the copper landline network, while competitors don’t have to. AT&T says it would continue providing landline service in areas where there is no alternative available.

However, CPUC rejected AT&T’s request. The agency says “AT&T failed to demonstrate the availability of replacement providers willing and able to serve as COLR.” The decision also cites public commenters who brought up the “unreliability” of mobile service and VoIP. AT&T is now pushing for new rules that would change the way California designates a COLR.

“No customer will be left without voice and 911 services,” Marc Blakeman, president of AT&T California, says in an emailed statement to The Verge. “We are fully committed to keeping our customers connected while we work with state leaders on policies that create a thoughtful transition that brings modern communications to all Californians.”