Sprint’s latest clever feat of financial engineering appears to be another success for the indebted wireless carrier.

The company is pricing $3.5 billion of bonds backed by some of its vast portfolio of airwave licenses. Sprint will segregate licenses worth $16.4 billion in a separate legal entity and then lease back the right to use the spectrum. The new entity will issue the bonds and use Sprint’s payments to cover the cost of its debt service.

Investors are set to snap up the bonds with an interest rate of less than 3.4%, the Financial Times reported on Thursday, or about half the rate Sprint would have had to pay if it issued the bonds without any backing.

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Majority-owned by Softbank Group, Sprint s has spent much of the past year looking for ways to raise money at the lowest possible rates to cover looming debt maturities of its own. Amid $37 billion of total debt, Sprint has $9 billion coming due in less than two years. Last year, it raised debt backed by leased phone receivables, and this year has used some of its cellular network equipment to back borrowings.

CEO Marcleo Claure has used savvy marketing campaigns—including one featuring Verizon’s former pitchman—with clever financial engineering to aid Sprint’s recovery. The moves have paid off this year as Sprint added 347,000 regular monthly phone customers in the quarter ended Sept. 30—five times what it added in the same period a year earlier.

And after adjusting for phone leases, Sprint had free cash flow of $707 million in the quarter compared to a cash loss of $100 million a year earlier.

Sprint said it used about 14% of its total spectrum holdings to back the new bond issue. The company could issue another $3.5 billion of spectrum-backed bonds in the future, Sprint has said.