Caves Beach resident Roma Heaven, 92, was stuck on the cold tiles until family members, who live in a separate upstairs residence, found her the next day.

"She must have been down there for a long time," Ms Heaven's son-in-law Steve Quigley said. "She had a big egg on her head."

The incident comes after Lake Macquarie City Council controversially approved the construction of a 36-metre-high Telstra telecommunications tower on Scenic Drive, Caves Beach in 2017. But more than three years later, it hasn't been built.

The Live Life Alert pendant is supposed to either trigger after a fall, or respond when a button is pressed, to alert up to five chosen contacts.

But the area's notoriously bad reception meant it didn't work, which Mr Quigley said was "very concerning".

"It's shocking really," he said. "She was in hospital for three days. We now go down and check on her before she goes to bed each night."

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Telstra NSW regional general manager Mike Marom said Telstra did not manage monitored alarm systems and any customers having issues "should talk to their provider to ensure they have are supplied a system that is appropriate for their circumstances", but said Telstra had been in contact with Mr Quigley about a mobile booster device to improve coverage in the residence.

Mr Quigley said Ms Heaven had suffered another fall since, but was thankfully wearing a different pendant which is connected through the home phone. But he is concerned about using this long term in the case of a blackout.

Lake Macquarie deputy mayor Christine Buckley and councillor Adam Shultz said they had regularly followed up resident inquiries to ask when construction of the tower would start, but said timelines had continually been pushed out, leaving the community with near non-existent mobile coverage.

They said the problem has become even more pronounced during the COVID-19 pandemic with more people working remotely.

"While we wait for this telecommunications tower to be installed, we hope and pray that lives are not put at risk," Cr Buckley said. "This has taken far too long to be completed and the community should have had a resolution way before now."

Mr Marom said while the development application was approved in late 2017, "this is only a part of the process of constructing and operating a new mobile base station facility".

"Agreements with a number of other external parties regarding site usage and access plus technical considerations such connection to power are also required," he said. "This can be a lengthy process at times with delays that are beyond Telstra's control.

"However, we expect to have all approvals and agreements completed in the next few weeks and barring unforeseen delays, hope to have the site completed and providing new coverage later this year."