The warning has come from Shropshire Councillor Heather Kidd, who is also the chair of the Local Government Association's (LGA) Safer and Stronger Communities Board.
The LGA said that criminals are exploiting the analogue to digital switchover to scam vulnerable residents who use health care telephony devices into giving out personal information such as bank details.
Around 1.8 million people use the devices nationally, but services that rely on the old landline system are being switched over to new upgraded landline services using digital technology.
The LGA, which represents councils, is concerned that the transition has created new opportunities for criminals to target vulnerable residents, potentially using phishing emails, fake websites or phone calls to trick them into providing personal information.
It is warning that scams could increase as the 2025 switchover date approaches, following a series of recent reports of criminals making calls to residents with health care devices claiming they need to hand over bank details as part of the switchover, or they will be disconnected.
The digital switchover is free and councils and home care alarm providers will never ask for personal or financial details over the phone.
Councillor Kidd said: "We are very concerned by a rise in criminals taking advantage of the digital switchover to trick vulnerable residents into giving out personal information such as their bank details. As the digital switchover date approaches, sadly we fear that further cases will arise.
"Councils will always act swiftly with the police where any incidents are reported, but we also urge people to be vigilant and help to raise awareness of this crime.
"The digital switchover is free of charge and residents should be aware that councils and their home care alarm providers or contractors will never ask for personal or financial information over the phone."
The LGA said councils are already taking steps to crackdown on switchover scams.
While the public switched telephone network (PSTN) upgrade is an industry-led process, the LGA is also calling on the Department for Science, Innovation and Technology (DSIT) to coordinate the multiple bodies involved with the switchover and support with raising awareness to ensure residents are prepared.
If residents are the victim of a scam or fraudulent activity they can report it to Action Fraud on 0300 123 2040.