Aquiss has accused BT of cold-calling its customers.
The firm, one of the UK's broadband suppliers, has issued a warning to its subscribers after an alleged 11 contract holders were contacted by BT, reports ISPreview.
According to Aquiss, BT made the calls under the pretence that work was being carried out at local telephone exchanges.
The provider suggested that customers who are signed up to the Telephone Preference Service could take action against BT.
Aquiss is quoted by ISPreview as telling its users: "BT Retail who these calls are from, have no awareness of engineering work going on at your local exchanges, and certainly likewise, they will not be aware that you have a broadband service provided by a non BT company (or certainly should not be aware!)."
A new 24Mb network is set to be rolled out by Aquiss in the near future after successful testing in the West Midlands.