US communications regulator the FCC has called for comments on how to proceed with the sale of a swathe of 700MHz spectrum no one wanted in the recent auction.

As expected, Verizon Wireless and AT&T were the big winners in the FCC’s 700MHz spectrum auction, which ended in March, spending much of the $19.6bn total.

But at the end of the auction, eight licences remained unsold, including the D block of spectrum which was reserved for the creation of a public/private partnership to build a nationwide public safety and commercial network.

The general consensus is that there were too many requirements attached to the D block and in its request the FCC asks whether it remains in the public interest to retain a public/private partnership between the D block licensee and the public safety broadband licensee.

As a result, the commission is seeking comment on various potential modifications to the current rules governing the requirements. One option is for the FCC to consider whether only entities that provide public safety services are eligible to use the public safety spectrum portion of the shared network.