California regulators pledged this week to create new rules for a stronger communications network by the summer, determined to fix failures that left millions without phone or internet service as blackouts proliferated and wildfires burned last year.

The California Public Utilities Commission said it will spend from March to May looking at what measures are needed before, during and after emergencies, including potential new rules for backup power, a step the telecommunications industry has opposed, with possible “fines and citations with noncompliance to our orders.” It will also consider what and when emergency responders should be told about critical outages.

Lawmakers are pushing for change, too. State Sens. Steve Glazer, D-Orinda, and Mike McGuire, D-Healdsburg, introduced a bill that would require companies to have 72 hours of backup power at cell towers in high fire-risk zones. Backup power options include batteries, which typically last a few hours, to a generator, which can run up to five days without refueling. Mobile cell sites — trucks brought on-site to bolster a network — can run for a couple of days.

In October, both senators’ districts were hit by wildfires, PG&E power shut-offs meant to prevent such blazes, and days-long communications service failures.

“Telecom representatives assured us this worst-case scenario, thousands of cell towers going down due to the lack of power, wouldn’t happen. It’s simply not true,” McGuire said in a statement. “It’s time California steps up and mandates cell towers have backup power.”

A similar bill McGuire sponsored last year that required 48 hours of backup power didn’t make it to a final vote. He now has a cosponsor, and public passions have been inflamed by last fire season’s conspicuous cell outages, as demonstrated by comments at other utilities commission hearings on the subject.

McGuire said in his statement that the bill “isn’t about checking your Facebook status. It’s about life and death and making sure Californians have a lifeline in their greatest time of need.”

In filings this week, AT&T and the California Cable & Telecommunications Association said they wanted to work to make the network more resilient in disasters. But AT&T urged regulators to decide what that means: Being able to make a call? Send a text? Load data to check emergency alerts? Or service comparable to everyday conditions?

The industry association said there are “significant, real-world challenges” like safety and environmental risks with installing gas-powered generators, as well as community opposition.

Telecommunications companies are regulated by the Federal Communications Commission as well as the California Public Utilities Commission. A past effort by federal regulators to mandate eight hours of backup power at cell tower sites failed after legal challenges from the industry. There are currently no requirements for backup power, but California has the power to change that, regulators say.

Another concern for regulators is timely information about outages. A law passed in the fall requires companies to provide outage information to public safety offices; another requires them to notify the Governor’s Office of Emergency Services. CalOES is working on finalizing what information companies should report and how by July.

At a November hearing, Verizon, AT&T, T-Mobile and Sprint committed to publicly disclosing data on cell towers out of service during outages. AT&T has a website that reports outages across its services, including landline and wireless phones, broadband and DirecTV satellite TV service.

Mallory Moench is a San Francisco Chronicle staff writer. Email: mallory.moench@sfchronicle.com Twitter:@mallorymoench