More than 30 million unlisted Australian mobile numbers have been made available for polling research, with just two companies accessing them so far.
Liberal polling company Crosby Textor and Tasmanian pollster EMRS both accessed the Integrated Public Number Database in May, five months after regulations were changed.
But the research industry lobby says it only found out about the change last week, despite publicly pushing for it for eight years.
Former communications minister Mitch Fifield changed the IPND rules in December 2018, giving de-identified numbers and postcodes to approved researchers for specific purposes.
Association of Market and Social Research Organisations executive director Sarah Campbell only became aware of the change just before an industry workshop last week.
"I can't comment on why we didn't know earlier, that's a question for government," she told AAP on Monday.
"I'm just really glad it's here because it's potentially of great value to research."
AMSRO has been lobbying for authorised researchers to get access to unlisted mobile numbers and the postcodes attached to their accounts to better target research.
The change was made on December 13 and posted on the Australia Communications and Media Authority website on December 17.
But neither ACMA nor the government would say whether the change was announced to the media or the research industry.
New Communications Minister Paul Fletcher says the industry knew the change process was under way.
"The industry is well aware of the regulations and were consulted with and engaged in the process early on following a review of the Integrated Public Number Database in 2015, which recommend the changes," his spokesman told AAP.
"The regulations went through the normal process for a disallowable instrument, including tabling in the parliament and publishing online."
Polling companies came under significant scrutiny after the May 18 federal election, in which Labor's long-held lead was proven to be a mirage in the voting booths.
Under the new regulations, researchers will get to access the IPND's unlisted mobile numbers and associated postcodes for public health research, commonwealth public policy research, or research relating to electoral matters.
Authorised researchers must pay a fee of several thousand dollars, and then pay one cent for each number they request. It's estimated more than 30 million numbers are now available.
Ms Campbell said access to mobiles was necessary because so many households were doing without landlines.
"Around 40 per cent of households don't have a fixed line now," she said.
The phone numbers and postcodes are provided to authorised researchers without identifying information, and research for commercial purposes is banned.
Australian Associated Press