The biggest US operators have committed to a set of “voluntary industry principles” related to device unlocking, with AT&T, Sprint, T-Mobile, US Cellular and Verizon Wireless all on board.

The move comes around a month after Tom Wheeler, head of the Federal Communications Commission, wrote to US industry association CTIA to warn that it is “now time for the industry to act voluntarily or for the FCC to regulate”.

The US regulator’s concern was related to a lack of support for the automatic notification of customers when devices become available for unlocking – which is now on the list of principles the operators are supporting.

Yesterday, Wheeler wrote: “Today, we see the manifestation of what I call the ‘see-saw rule’ – the more industry acts to meaningfully regulate itself, the less that has to be done by government”.

But this was not without a caveat: “Our goal here was not to find agreement, congratulate all involved, and then file this document away never to be seen again. With industry input, the FCC will collect and review feedback through a website that allows consumers to access carrier policies directly, read FAQs, including information that explains technological limitations, and file complaints should there be any concerns about compliance with the agreement.”

The five have also committed to: post unlocking policies on websites in “clear, concise and readily accessible” terms; unlock contract devices on expiry of the agreement, settling of a finance plan, or payment of an early termination fee; and unlock prepaid devices “no later than one year after initial activation”, consistent with “reasonable time, payment or usage requirements”.

The operators will also unlock devices or initiate requests to OEMs to unlock devices, provide an explanation of why an unlock is not possible; or detail why additional time is needed to process a request, within two business days of contact by a customer.

And for military personnel deployed overseas, operators will unlock devices for those “in good standing upon provision of deployment papers”.

The five will still be able to decline an unlock request if there is a reasonable belief that the request is fraudulent or a device is stolen.

Three of the six items will be adopted within three months of the adoption of the commitment, with the remaining three within 12 months – CTIA did not reveal how this would be split.