The Corporate TPS is designed to give businesses the same rights as individuals to opt out from receiving telemarketing calls.
But critics of the service provided by DMA subsidiary, the Telephone Preference Services, as part of its contract with Ofcom, say it is an over-reaction with fines of £5,000 for those breaking the rules.
The British Chamber of Commerce has gone further and called it another tax on business.
The service enables limited companies in the UK, limited liability partnerships in England, Wales and Northern Ireland, and any partnerships in Scotland as well as schools, government departments and agencies, hospitals and other public bodies to register with the Corporate TPS.
Colin Lloyd, chairman of TPS, said: "Now that this significant piece of legislation has come into force, it is vital that as telemarketers, we are fully compliant with the regulations."
However, compliance does not come cheap. It will saddle business with a £4,000 annual bill, which will hit small businesses hard pushing them critics say to consider switching business to India.
The criticism has been dismissed by the government, which said it widely consulted before putting the new "do not call" rules into operation.
Stephen Timms, minister of state for energy, e-commerce and postal services, said: "The DTI consulted widely on the introduction of Corporate TPS last summer and I believe we have achieved the right balance between enabling direct marketing organisations to target potential customers effectively while protecting companies that prefer not to receive cold calls at work."
Corporate subscribers can register with the Corporate TPS at .
If subscribers are unable to register online they can also register via email, post or fax, but not by phone.
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