Sprint, DirecTV and seven other groups are asking the FCC to stall its review of Verizon's $3.9 billion AWS purchase because of problems accessing documents about the transaction.

Stopping the FCC's self-imposed shot clock on the transaction could be a setback for Verizon, which has said it expects the purchase of nationwide AWS licenses to close this summer.

The companies claim that they have encountered "delays and technical difficulties, including files that cannot be opened with software commonly used by law firms" when attempting to access documents provided by Verizon and its four cable partners.

Reviewing the documents is vital to properly assess the spectrum sale, but some can only be accessed with "expensive" software, they said.

"Organizations and firms that do not have this expensive software … have been seriously challenged in their attempts to search through the daunting volumes of files and review relevant documents," the groups said in a letter sent yesterday to the FCC.

The document was signed by Sprint, DirecTV, FairPoint Communications, Free Press, Media Access Project, Open Technology Initiative, Public Knowledge, the Rural Cellular Association and the Rural Telecommunications Group.

"Considering the delays in receiving data and the technical challenges involved, the Commission should take the further step of giving reviewers the additional time that is necessary to study the documents and data and respond to the Commission with cogent analysis," they said.

The letter followed a similar request from the Communications Workers of America last week. The union expressed "concern about not having a timely and meaningful opportunity thus far to review documents" and asked the FCC for more time.

A Verizon spokesman said the operator complied with the FCC's document requests.

"Verizon is cooperating fully with the FCC in responding to its requests and in getting it the information it needs," he said.

The FCC has not said whether it will extend its review process, but there is recent precedent for delaying proceedings. The agency pushed out the deadline on its review of AT&T's merger with T-Mobile USA to analyze additional information about the buyout.

Verizon CFO Fran Shammo said during the company's earnings call last week that it expects to receive FCC approval for its AWS purchase by mid-summer.

Despite its apparent confidence that the transaction will go through, Verizon recently attempted to sweeten the deal by offering to sell off its lower 700 MHz A-block and B-block assets if the FCC agreed to let it buy the AWS spectrum.

T-Mobile USA, an opponent to the AWS deal, did not appear impressed about the offer during a recent meeting with the FCC.

"This proposed sale does not mitigate the substantial public interest harms created by Verizon’s pending transaction with the cable companies," T-Mobile said in an ex parte filing last week that documented the meeting.

T-Mobile, MetroPCS and other groups opposed to Verizon's spectrum grab claim the deal will consolidate too much spectrum in the hands of a single operator. Verizon said it needs the additional bands to add capacity to its LTE network.