In an era when nearly everyone has a cellphone and digital communications are widespread, it can be tough to remember that, for some people in America, an old-fashioned telephone still feels like a crucial lifeline.

But there was no mistaking its importance to Mary Hamill - not when I heard the series of breathless voice mails she'd left while I was out of the office for a few days.

"I need your help desperately," her first message said. "I'm afraid I'll have a heart attack and be unable to call 911."

Hamill, 85, complained that Verizon had cut off her phone because of missed payments while she was away in Florida and a subsequent tiff over a missing check. Now, she said, the utility was failing to address the problem despite her ill health.

Later, Hamill told me that Verizon had restored her service, but with a number different from the one she'd had for years. And she complained that her phone was working only intermittently. Without it, she worried, "I couldn't call my doctor, and my doctor couldn't call me."

Hamill contacted me because of previous columns about customers' disputes with phone companies, but it was clear hers was messier than many.

After I called Verizon, company spokesman Lee Gierczynski said Hamill's previous number would be restored, explaining that a new number was assigned because technicians treated her line as a new account.

Still, Gierczynski said Verizon had done everything by the book. Technicians have "tested and retested" Hamill's phone and found nothing wrong. As for the billings leading to Hamill's cutoff, he declined to comment for privacy reasons. But he said this much: "All the policies and procedures were handled properly with her account. And nothing in the record indicates that the disconnection was handled improperly."

Hamill insists something went wrong at Verizon's end, at least after she sent in a check when she returned from her annual trip to Bradenton, Fla., and discovered her phone disconnected. When service still didn't return, she called and was told no payment had been recorded.

"I said it's not my fault they couldn't find the check," said Hamill, a West Catholic graduate who spent 40 years working for Verizon's Bell Telephone predecessors, including handling billings. She insists she never saw at least some of the invoices in question.

Was this a small dispute to which Verizon overreacted, perhaps complicated by Hamill's Florida trip, or a larger matter that left the company no choice but to disconnect Hamill?

I did have occasional trouble reaching Hamill last week, but I can't sort out the financial fight. She acknowledges paying more than $400 via credit card to reinstate the account - enough to cover several months of phone and TV at her Berwyn apartment.

So let's call a truce on the tit for tat, and consider some of the broader issues her story raises.

One is: Are there special rules to protect those who need access to emergency phone service?

The short answer is yes. Even a phone that's suspended - though not one disconnected, as Hamill's was - should work for an emergency call to 911, according to Jennifer Kocher, spokeswoman for the Pennsylvania Public Utility Commission. Though Hamill doesn't have one, cellphones offer similar emergency calls.

Broadly speaking, technological changes - and looser regulation of the wireless and broadband industries - have complicated state regulators' ability to oversee phone providers, and to intervene when something goes wrong.

For instance, the PUC has no jurisdiction over cable companies such as Comcast that provide the Internet-based phone service known as VOIP. And it has limited power over carriers such as Verizon that provide both VOIP and non-VOIP phone services.

Sometimes, it's not obvious what you've got. Before her cutoff, Hamill had FiOS TV packaged with traditional, circuit-switched phone service. Now, she gets a deregulated, fiber-based bundle.

When in doubt, Kocher suggests calling the PUC's consumer-help line: 1-800-692-7380. (In New Jersey, call the Board of Public Utilities at 1-800-624-0241.) Since 2009, the PUC has been able to patch Verizon customers through to a special problem-resolution team. And state regulators can steer other kinds of problems to whatever resources are available - including to the attorney general for intractable complaints.

Contact Jeff Gelles at 215-854-2776, jgelles@phillynews.com, or on Twitter @jeffgelles. Read his blog at www.philly.com/consumer.