In a ruling released Thursday, the high court said it would not hear an appeal by the phone companies that were trying to have the suit thrown out. Lower courts had allowed the lawsuit to proceed. The Supreme Court gave no reason for its decision not to hear the case.
The ruling means the suit will be handed back to a lower court to be heard.
Units of the three big phone companies — Bell, Rogers and Telus —are named as defendants, along with a number of smaller players, including SaskTel, MTS Allstream and Bell Aliant.
"We appealed this because we believe the case was not properly presented to the courts as a class action," Telus said in a statement.
"The appeal was a procedural process, and there's been no finding on the merits of the case itself. We are confident the case is without merit and baseless, at least as it related to Telus."
The suit was launched in 2004 and was first certified by a Saskatchewan court in 2007.
It alleges that Canadians have been misled by the carriers into thinking the access fee — typically between $6.95 and $8.95 a month — was a tax by the government or the Canadian Radio-television and Telecommunications Commission, when in fact it was simply extra revenue for cellphone companies.
The suit was filed on behalf of more than 14 million monthly cellphone subscribers, or nearly half the country's population, and seeks the return of an estimated $12 billion, plus interest charges. That would result in a total claim of about $19 billion, or about $600 to $700 per customer.
Many companies have since phased out system access fees. But the suit is seeking damages to compensate customers for paying those access fees many years ago.