Alchemis chief executive Ian Forbes carried out an impromptu survey to find out whether staff in companies that had signed up to the TPS were aware they were registered.
One of the companies he found unknowingly registered was his own.
"It became evident after several calls that there was a trend," Forbes said. "Company after company were telling us that they had no idea that their numbers were registered. When I checked, purely out of curiosity to see if our own switchboard number was registered, I was amazed to see that it was."
The survey of 30 companies selected from the Corporate TPS list at random found that 44% of the people who picked up the phone had no idea that their company was registered.
The results also showed that out of those that knew the number had been registered, 36% were not consulted on the issue. Only 36% of all respondents were directly responsible for registering the number, while 68% had noticed no effect on the number of calls since registration.
The Corporate TPS became law in June this year and has been enforceable since July. It enables companies to register telephone numbers in order to protect them from cold-calls by companies wishing to sell products or services.
Forbes said that these results present the Direct Marketing Association, which runs the TPS, with a worrying dilemma.
"If 44% of numbers are being registered without the knowledge of the person picking up the phone, who is registering them? And how effective can the law be if employees aren't informed?"
He said that Alchemis approached the TPS about the process and was told that no proof of status was required in order to register a number.
"We have been concerned that this new law is not being implemented properly. I have been told by the TPS that no proof of status is required, which is hugely worrying for businesses. Although it may be a worse-case scenario, it seems that there is nothing stopping a company from registering a competitor's switchboard number," Forbes said.
DMA spokesperson Liz Bastone said safeguards were in place. She said a record was taken of the person registering, who was required to leave their details including job title.
"Registration is only accepted in writing and is confirmed in writing. The majority of companies only register one number," Bastone said.
If you have an opinion on this or any other issue raised on Brand Republic, join the debate in the .