The wireless providers, which have been in merger talks since late last year, are teaming up to bid in a 2015 auction of television broadcasters’ airwaves, according to The Wall Street Journal.

T-Mobile will lead the partnership, while the funds will likely come from the $45 billion financing package being constructed by SoftBank Corp to enable Sprint’s purchase of T-Mobile, people with knowledge said.

SoftBank, led by chairman Masayoshi Son, bought Sprint last year for $22 billion.

The setup is subject to change as talks continue, but a joint venture would allow Sprint and T-Mobile to participate in the auction as a single entity without stepping out of legal bounds.

A Sprint acquisition of its U.S. counterpart could still come later this summer, though the company has said regulatory approval could take longer than usual.

U.S. regulators insist on maintaining four wireless competitors in the marketplace, where Sprint and T-Mobile are No. 3 and No. 4. AT&T’s effort to buy T-Mobile in 2011 was shot down by the U.S. Justice Department.

AT&T (ATT) has set aside $9 billion for the spectrum auction. The Sprint-T-Mobile duo would be on equal footing with their $10 billion firepower. Verizon (VZ) has not said specifically how much it plans to spend.

The joint venture will allow the two smaller companies to compete effectively against AT&T and Verizon in the auction led by the U.S. Federal Communications Commission, which is buying low-frequency airwaves from television broadcasters to then resell them to wireless carriers. This is the first time the FCC has conducted such a sale.

Low-frequency spectrum is highly desirable because it travels farther and penetrates buildings better, reducing the need for cell towers. Wireless carriers are anxious to secure this spectrum as demand for mobile data surges.

AT&T and Verizon already own most of the low-frequency spectrum in use, and Sprint and T-Mobile have pushed the FCC to set aside a portion of the auction specifically for smaller companies. The Justice Department forced the issue, and the FCC set aside a minority share for Sprint and T-Mobile. That still leaves AT&T and Verizon in a position to purchase most of any spectrum made available.

The restricted spectrum access could help justify Sprint’s purchase of T-Mobile, the WSJ reported. If the FCC won’t ensure that smaller players get enough airwave access, the companies could maintain the only way to get it is by merging.