The wireless industry has for years successfully fought regulations that would force mobile phone networks to be hardened so they work during storms, but it may face renewed demands after Hurricane Harvey knocked out seven of 10 cell towers in the hardest-hit counties of Texas.

Across the 55-county disaster area in Texas and Louisiana, nearly one in 20 sites were out right after the storm, according to the Federal Communications Commission. In the state's biggest city, Houston, 5.1 percent of cell sites weren't working.

"The wireless industry has done everything it can to persuade federal regulators and state regulators not to require that backup power be put in place," said Regina Costa, a committee chair of the National Association of State Utility Advocates, which speaks for consumer representatives. "It's a huge public safety issue — because in order for communications to work there has to be power."

The FCC imposed power backup requirements after Hurricane Katrina in 2005 knocked out more than 1,000 cell sites — roughly triple the number of power failures seen with Harvey. The rule never took effect as the wireless industry fought it in court. Since then, the FCC has considered but not adopted similar requirements.

Harvey could refocus the agency. FCC Chairman Ajit Pai is set to visit Texas to inspect damage on Tuesday. Further steps may be needed to ensure that storm victims can report emergencies in the future, said FCC Commissioner Jessica Rosenworcel. "As waters swell and Houston reels, this agency needs to get to work," Rosenworcel, a Democrat, said in an e-mail.

Wireless companies readied backup generators, positioned fuel and brought in emergency response teams ahead of Harvey making landfall, according to CTIA, a trade group with members including AT&T Inc. and Verizon Communications Inc. Asked about the calls for backup power, CTIA spokesman Justin Cole said that carriers have worked closely with government officials and have kept wireless coverage at 95 percent across the area impacted by Harvey, while emergency call volume has increased.

In Texas, the system has held up well considering Harvey's size and power, said Jamie Barnett, a partner at Venable LLP and a former chief of the FCC's public safety bureau.

The bureau settled in recent years on endorsing a voluntary framework where the wireless industry pledges steps to improve emergency readiness.

Shields writes for Bloomberg.