When her 19-year-old daughter died of injuries sustained in a Mother’s Day car crash five years ago, Lisa Moore sought comfort from the teenager’s cellphone.

She would call daughter Alexis’ phone number to listen to her greeting. Sometimes she’d leave a message, telling her daughter how much she loved her.

“Just because I got to hear her voice, I’m thinking ‘I heard her.’ It was like we had a conversation. That sounds crazy. It was like we had a conversation and I was OK,” the Terre Haute, Ind., resident said.

Moore and her husband, Tom, spent $1,700 over the past five years to keep their daughter’s cellphone service so they could preserve her voice. But now they’re grieving again because the voice that provided solace has been silenced as part of a Sprint upgrade.

“I just relived this all over again because this part of me was just ripped out again. It’s gone. Just like I’ll never ever see her again, I’ll never ever hear her voice on the telephone again,” said Lisa Moore, who discovered the deletion when she called the number after dreaming her daughter was alive in a hospital.

Technology has given families like the Moores a way to hear their loved ones’ voices long after they’ve passed, providing them some solace during the grieving process. But as they and so many others have suddenly learned, the voices aren’t saved forever. Many people have discovered the voices unwittingly erased as part of a routine service upgrade to voice mail services.

Often, the shock comes suddenly: One day they dial in, and the voice is inexplicably gone.

A Sprint upgrade cost Angela Rivera a treasured voice mail greeting from her husband, Maj. Eduardo Caraveo, one of 13 people killed during the Fort Hood shootings in Texas in 2009. She said she had paid to keep the phone so she could continue to hear her husband’s voice and so her son, John Paul, who was 2 at the time of the shooting, could someday know his father’s voice.

“Now he will never hear his dad’s voice,” she said.

Jennifer Colandrea of Beacon, N.Y., complained to the Federal Communication Commission after she lost more than a half dozen voice mails from her dead mother while inquiring about a change to her Verizon plan. Those included a message congratulating her daughter on giving birth to a baby girl and some funny messages she had saved for more than four years for sentimental reasons.

“She did not like being videotaped. She did not like being photographed,” Colandrea said of her mother. “I have very little to hold onto. My daughter will never hear her voice now.”

Lisa Moore finds it hard to believe Sprint can’t recover the message.

“I can’t believe in this day and age there’s nothing they can do for me,” she said.