If T-Mobile is not growing, it is hard to justify spending millions of dollars on 3G network upgrades and subsidies for new smartphones, analysts said. "This business is very cash intensive, making it difficult to bid for top handsets and it takes cash to bring customers good networks," Stofega said.

T-Mobile said in January that it had specification called HSPA 7.2 to 200 million people in the U.S., after more than a year of development.

However, Stofega said is still a widespread perception that T-Mobile has an "inferior network" at the same time that T-Mobile "is certainly facing big guns in Verizon, AT&T and, for that matter, Sprint."

T-Mobile's network upgrade might have come too late to help, said one independent analyst, Jeff Kagan. "They are rushing to catch up ... with AT&T, Verizon or Sprint," he said. "Their speeds are not as fast in as many places."

Kagan said that T-Mobile focused too long on offering cheap wireless phone calling, instead of fast wireless Web connections, after being created in 2001 when Deutsche Telekom purchased VoiceStream Wireless.