People in Mansfield are being warned about bogus workers trying to sell aerials ready for the digital switchover next year.
The district council said the men are claiming to work for the local authority and are targeting tenants in some sheltered housing and homeowners.
Analogue channels in the area are due to be switched off in September next year.
The council said tenants on a communal aerial system would not need a new one.
Any upgrading of aerials or equipment is being done by F1 Aerials on behalf of the council.
A Mansfield District Council spokesman said: "We urge residents to be on their guard to this scam, especially as people may be expecting additional work to be carried out before the digital switchover next year.
"F1 representatives will have a letter on headed council paper stating they are the official council contractor."