The Federal Communications Commision needs more time to consider whether to approve a multibillion-dollar merger between Sprint and T-Mobile.

The FCC sent a letter to the two companies Tuesday, explaining that “additional time is necessary to allow for thorough staff and third-party review of newly-submitted and anticipated modeling.” To review the new materials, the commission is pausing an “informal” 180-day shot clock to rule on the merger.

The clock will remain paused until T-Mobile and Sprint are finished submitting documents and information about the merger, and until the commissioners feel they have had enough time to review the record.

In April, T-Mobile and Sprint agreed to merge and create a $146 billion company called simply, T-Mobile. T-Mobile CEO John Legere would remain chief executive of the combined company. Its primary headquarters would be in T-Mobile’s hometown, Bellevue, Wash.

In June, the two companies began pleading their case to the FCC, which will have to sign off on the merger for it to go through. In their joint Public Interest Statement, T-Mobile and Sprint claimed that the merger would increase competitiveness in the wireless landscape, allowing the combined company to take on incumbents Verizon and AT&T. They also claimed the merger was integral for the U.S. to remain competitive in 5G, the next generation of super-fast wireless technology.

Earlier Tuesday, T-Mobile announced it was putting another $3.5 billion into 5G hardware and software in a deal with Ericsson, stating that it was, “laying the groundwork for 5G and with Sprint – and with Sprint we can supercharge the 5G revolution.”