T-Mobile US has leased its spectrum to other carriers in an effort to expand its LTE network to benefit their customers. 

However T-Mobile has declined to comment on how many carriers it has leased spectrum to, what spectrum bands were leased, or how much territory those leases cover. "T-Mobile is always looking for the right opportunities to improve its network," the spokesperson said in a statement. "This includes spectrum swaps, leasing spectrum and roaming agreements. We'll continue to discuss additional opportunities as they arise and make the best decision to benefit our customers." 

T-Mobile's spectrum-leasing efforts appear to be a less formal version of Verizon's LTE in Rural America (LRA) program and Sprint’s rural LTE program. 

Verizon has signed up 21 rural and smaller carriers to the program, and 19 have launched LTE networks via the program. Verizon covers 224,000 square miles under LRA agreements and 100,000 square miles with live LTE networks. Fully 2.9 million people are covered by the leases and there are more than 900 LTE cell sites live in LRA territory.

Sprint operates a similar leasing program. The carrier counts a total of 27 carriers in its rural LTE program, covering 565,000 square miles in 27 states and a population of more than 38 million people.