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T-Mobile owes a large part to its 2015 successes to competitors like AT&T, CEO John Legere said Wednesday.

"The biggest donator last year was AT&T. AT&T contributed to the benefit of the rest of us with 1.5 million [postpaid customer] losses on the [year]," Legere told CNBC's "Squawk on the Street." Postpaid phone plans are those where the consumers' monthly bill is dependent on their usage.

"Now, Sprint has been kind of a long-term contributor [to us] of postpaid phones [although] lately, they've had a small gain," he said. "All of them, dumb, dumber, and yellow, contribute heavily to the un-carrier revolution."

Legere made his remarks after the company reported fourth-quarter earnings per share of 34 cents, on revenue of $8.25 billion. Analysts polled by Reuters expected 15 cents EPS on revenue of $8.20 billion.

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"Postpaid phone nets are the core of our industry," Legere said. "The average revenue per postpaid user … is much higher, and we've built off of that into the derivation value to the company."

Shares of T-Mobile were 1.75 percent higher in afternoon trading.

Legere also took a shot at Verizon, saying the company is "afraid" of T-Mobile's rise. "Verizon forever has lived on the fact that they've had the better network. We now cover 98 percent of America that Verizon covers and for eight quarters, we've been the fastest 4G LTE, and they know it."

Chuck Hamby, Verizon's director of corporate communications, told CNBC in an email: "Anyone can make outrageous claims, but at some point you have to put up or shut up."

"Verizon's national network covers 2,385,306 ... square miles and 312 million Americans with LTE — more than 98% of U.S. population. T-Mobile:1.3 million square miles and 304 million covered by LTE. That is a huge difference to the 8 million people and businesses who live and work in those 1 million+ square miles."

Michelle Boyd, media relations manager at Sprint, said in an email: "Here's what I will say, we announced our FY15 Q3 results on January 26 and clearly we are making progress with our turnaround efforts and are gaining postpaid phone subscribers."

"Sprint delivered positive phone net additions for the 2nd quarter in a row, and we had the highest postpaid net ports on record in Q3 and positive for 4th consecutive quarter."

AT&T did not immediately respond to a CNBC request for comment.

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Legere also commented on Apple CEO Tim Cook opposing a federal court order to help the FBI in lock the iPhone used by one of the San Bernardino terrorists.

"I wouldn't know how to advise him but I understand both sides of the issue," Legere said.

"I think it's groundbreaking. We value security and privacy for our customers at the paramount basis. But the questions right now associated with national security and the horrific accident where 14 people were killed, I really don't know how to balance it."

Apple received the order Tuesday and has five days to formally oppose it.