The networks have batted away suggestions from a dealer group that they have failed to police the independent channel.
The Mobile Broadband Group (MBG), which represents the interests of all five networks, said its members had made 'strenuous efforts' to enforce the voluntary code on cashback and misselling, signed by the operators last summer.
At a press conference in Westminster yesterday the Independent Mobile Phone Dealer Association (IMPDA) called for the introduction of an independent dealer accreditation scheme to put a stop to unscrupulous re-sellers.
The IMPDA alleged that as well as not enforcing the code, networks have encouraged dealers to base their cashback propositions on low redemption rates - a charge refuted by the MBG.
And the MBG cited the '100s of dealers who have had their contracts terminated' as evidence of their enforcement of the voluntary code.
The MBG added that it wanted to maintain 'a healthy, competitive and independent dealer channel'.
Paul Hull, spokesman for the IMPDA, said: 'Networks keep saying they want the dealer channel - they need to prove it.'