LAVEEN, Ariz. -- A Laveen man got a cell phone bill for $23,000 without using a minute of air time.

Ceasar Hernandez has an 84-year-old grandfather caught in the middle of an ID fraud scheme.

“It's upsetting that he's having to go through this," Hernandez said.

He said someone used his grandfather's name to get a cell phone.

"If you knew my grandfather, he'll do anything for you and it's a shame that he was taken advantage like this," Hernandez said.

The family said they discovered it after he got a Sprint bill for more than $600. Then a second bill arrived from Alltel for $200.

A collection notice from Sprint arrived just a few days ago. The notice for was an unpaid debt of $23,000.

"I just can't imagine how you can get that kind of figure from a cell phone and cell phone usage," Hernandez said.

Hernandez said his grandfather doesn't even own a cell phone from Sprint or Alltel.

"This is two hits on his credit he doesn't need right now," he said.

CBS 5 News called Alltel but the company did not return the calls. A spokesperson for Sprint said the company work regularly with local authorities.

Hernandez said the family has able to dispute the Sprint bills but they're still working on clearing up the Alltel one.

The family said it is now focused on repairing the damage, clearing up his grandfather's credit and restoring his faith in people.

"This might make him a little more leery to help somebody or go out of his way knowing that they're going take advantage of him."

The Maricopa County Sheriff's Office said it is investigating the incident.