Galaxy Note 7 owners in the US who have ignored the global recall of Samsung's smartphone face a fresh effort to make them return their devices.
Mobile network Verizon told Fortune magazine that it planned to divert calls made via the phones so that they reached its staff instead.
It follows dozens of reports of the devices overheating and in some cases bursting into flames.
Samsung is expected to reveal the cause of the problem on Monday.
It pulled the product from the market and cancelled further production in October after an earlier botched recall and re-release.
US operators had already released a software update intended to prevent Note 7s from being able to recharge and connect to their networks.
But Verizon said that thousands of its customers had still not returned the devices, possibly because they had managed to prevent the firmware from being installed.
"The recalled Note 7s pose a safety risk to our customers and those around them," it told Fortune.
It said it would still allow 911 calls to connect to the emergency service, but all other calls would be redirected to its employees, who would demand the return of the handsets.
Customers who refused might be billed the full retail cost of the device, it added.
"This is all about liability," commented Ben Wood from the CCS Insight tech consultancy.
"People may be willing to accept the risk now, but that could change if they experience a catastrophic incident like it burns down their house or seriously injures someone.
"Samsung and the operators have no option but to put whatever measures in place they can to try and retrieve all the remaining devices."