T-Mobile is calling on federal regulators to step up in providing clarity on the impact of government operations in the AWS-3 spectrum due to be auctioned in September.

The FCC plans to auction off 65 MHz—1695-1710 MHz, 1755-1780 MHz, and 2155-2180 MHz bands—of AWS-3 spectrum, which will be used on a shared basis for commercial wireless and incumbent government operations for a transition period following the auction.

In a blog post, T-Mobile said more work needed to be done to ensure potential bidders understand the possible impact of federal incumbency, relocation timelines, and the potential for temporary or indefinite sharing of the spectrum.

“Without additional clarity about the impact of government operations in the band, wireless carriers’ bidding strategies will have to be made in a vacuum, potentially depressing auction participation and revenues,” Steve Sharkey, a senior director of government affairs at T-Mobile, said in a statement.

T-Mobile insisted that information on the source of federal systems operating in the bands be made available soon to allow potential bidders to “evaluate mitigating factors and better judge the potential for successful coordination.”

The FCC recently announced a band plan for the AWS-3 auction, increasing the amount of 5x5 MHz blocks available for bidding, a move that drew praise from T-Mobile.

But AT&T was less supportive of the FCC’s smaller block sizes, saying the lack of 10x10 MHz blocks in the AWS-3 auction could impair the provider’s 10 x 10 carrier aggregation plans.

T-Mobile has projected the AWS-3 auction revenue will total $6.3 billion to $9.4 billion.