“Use it or lose it” is the policy under which the Federal Communications Commission licenses scarce, publicly owned airwaves, but in practice companies warehousing unused spectrum can sell it off and make a handsome profit.

Reuters today reports T-Mobile USA is exploring a spectrum buy from its rival Verizon Wireless to bolster wireless data services to effectively compete against Verizon, AT&T and Sprint.

A source told Reuters the deal is in the early stages and could involve the purchase of Verizon’s unused “A” Block 700MHz spectrum, ideal for long distance and indoor reception. Verizon chief financial officer Fran Shammo earlier said the company was not going to sell its unused spectrum at “fire sale” prices and recently rejected an offer deemed to be too low. One analyst estimated the value of Verizon’s excess “A” spectrum to be as high as $3 billion.

T-Mobile, owned by Deutsche Telekom, told investors on Nov. 12 it was launching an equity offering to raise money for spectrum deals with a private, unnamed party. T-Mobile raised $1.8 billion through a sale of its common stock last week and offered $2 billion in bonds on Nov. 18 with the expected aim of funding future spectrum purchases.

Verizon acquired the spectrum in 2008, part of a broader auction that sold off frequencies formerly used by UHF TV channels 52-69. The “A” block is considered less desirable because of adjacent interference concerns in areas where a television station operates on Ch. 51. Those stations may not be there for long. The FCC is proposing to auction off UHF channels 31-51 to wireless companies in the future, reducing UHF TV to channels 14-30. Verizon’s “A” block licenses do not blanket the entire country, but can cover a number of major cities. Verizon Wireless deployed its LTE 4G network on its “C” block.