The new rules have been put in place to prevent any company selling phones and phone services from engaging in "dishonest, misleading or deceptive conduct".
They replace the voluntary code introduced in 2007, which Ofcom said failed to reduce consumer complaints.
Network operators will now have to ensure the customer intends, and is authorised, to enter in to a contract – of which they know all the terms and conditions.
This includes any details of cashback deals and exactly how customers are able to get their money back.
This has been one of the most significant increases of complaints, with customers finding themselves signed up to a more expensive tariff than they were originally sold, only to find out they have to claim cashback after paying out the full whack.
Other complaints include customers being sold a service on the promise of good coverage in their area, only to find they have next to no reception.
Now any providers found to be breaking the rules could be fined up to 10% of the relevant turnover.
Have you ever felt you were mis-sold a phone or phone service? We're interested to hear your stories, so let us know below or have a vent over on the forums.
Via: Press Association