Dorothy Clark, 83, had gone down for a nap on Jan. 4. As was her routine, she took each of her phones off their hook; she frequently received calls from telemarketers and did not want to be disturbed.

A few hours later, she woke up and turned on the shower. Then everything dropped out from under her.

This had happened to Clark before, she said; these sudden fainting spells. As she described it, gravity snuck up from behind and she would fall backward. Doctors hadn’t been able to find the cause, she said.

She regained consciousness on the floor next to her bathtub, unable to pick herself up. The water — long cold now — had begun flowing over the edges of the tub basin, cascading over her exposed body.

Clark remembered her Lifeline, the medical alert bracelet her daughter had purchased a few years before for just such an emergency. She pressed the button. Nothing. Again. Nothing.

She stayed that way for more than 10 hours, shouting at the top of her lungs for help.

“I kept telling myself, ‘Dorothy, you’re a very strong person,’” Clark said. “I knew I was going to die of hypothermia if I didn’t get out of there soon.”

Finally, a neighbor heard her cries and called the fire department.

Two months later, Clark is physically unscathed from her fall and is biding her time in a temporary senior living apartment while her home is repaired for water damage. But she’s piping mad at the installers of her Lifeline bracelet.

It’s not that the bracelet failed. The Philips Lifeline medical alert bracelet works by transmitting its signal to a receiver connected to the owner’s landline phone. But if there’s no dial tone — as was the case after Clark took her phones off the hook — the signal won’t go through to the service’s staff.

This aspect of the device, Clark said, was never properly explained to her.

“If I were a salesman, I’d take the phone off the hook and say ‘If your phone’s off the hook like this, it won’t work,’” she said. “How hard is that?”

She added that she thought the explanation should have especially been given since she is sight impaired, and could not readily read the instruction manual.

After the incident, Marcia Meneghini was helping out at her friend Clark’s home when she noticed the state of the phones. She replaced the receivers when the Lifeline system buzzed and a call immediately came through inquiring whether there had been a fall. Menegheni confirmed and told the representative the incident was over.

What annoyed Marie Brokenicky, Clark’s daughter, was that the whole situation could have been avoided with just a little more information about phone accessories on the market, she said.

“I was told after the fact — from the phone company, not the Lifeline people — that there’s a device that connects to the phone that would allow the medical alert to work even when the phone is off the hook,” Brokenicky said, speaking during a trip to visit her mother. “It’s not expensive; only $100 or so. And we really would have appreciated knowing that was an option.”

Clark does not plan to pursue litigation against Philips, she said, but she will be contacting the Better Business Bureau.

“I want other people to know the situation, so what happened to me won’t happen to them,” she said.

Philips Co.’s media communications department has not responded to requests for comment.