Boost Mobile, a unit of Sprint Nextel, told Reuters today that it added six times more subscribers than it lost since the rollout of its unlimited plan.

Boost unveiled its $50 unlimited plan in mid-January as a way to stay competitive in a prepaid market that is increasingly pitting itself against larger postpaid carriers.

Boost's comments address concerns that prepaid carriers suffer from considerably higher churn rates than do postpaid carriers that secure customers with contract-based plans.

The $50 price for unlimited service is lower than offers from postpaid carriers and at about the same level as those offered by other prepaid carriers like MetroPCS and Leap Wireless International.

Analysts see Boost as a bright spot for Sprint Nextel, which announced fourth-quarter earnings today, reporting a $1.62 billion loss.