The FCC should not fully charge universal service fees to customers whose wireless phones are not their primary phones, officials from the CTIA said in a letter to the Commission, citing recent AT&T and Verizon Wireless proposals.

Such customers represent 40% of all U.S. wireless customers. They should only have to pay partial fees, the industry lobbyist group said.

“Imposing a full numbers-based assessment on wireless prepaid and ‘non-primary’ wireless family-plan customers would result in significant rate shock. The universal service contribution for the typical wireless ‘family plan’ subscriber would almost quadruple,” the CTIA said.

Various changes to the Universal Service Fund have long been controversial for the wireless industry. The issue arose in 1997, 2002, 2004, and earlier this year.