UPDATE 2-Virgin Mobile USA Q1 profit tops Street; shrs jump

* Q1 adj. EPS $0.24 vs est. $0.10

* Q1 rev $337.3 mln vs est. $359.4 mln

* Shares jump 29 pct before the bell (Adds background, details from conference call, shares)

May 11 (Reuters) - Virgin Mobile USA Inc VM.N posted a quarterly profit that handily beat market estimates on the success of its "hybrid" service plans and said its average revenue per user would rebound in the second half of 2009, sending its shares up 32 percent.

Hybrid plans, which have some benefits of both prepaid and postpaid options, offer customers fixed number of minutes at a standard price without a contract.

Average revenue per user (ARPU) for the wireless service provider was almost flat for the quarter due to the ongoing consumer trend of the replacement of voice minutes with messaging.

While the company -- partly owned by Richard Branson's Virgin Group [VA.UL] -- expects to continue see ARPU dampening in the second quarter, it said the trend would reverse in the second half of the year.

Last month, Virgin Mobile USA launched a $49.99 unlimited plan. A slew of companies are battling it out in the fast-growing low cost segment as US consumers pinch pennies in a down economy.

Apart from MetroPCS (PCS.N: Quote, Profile, Research) and Leap Wireless (LEAP.O: Quote, Profile, Research), Sprint Nextel (S.N: Quote, Profile, Research) unit Boost Mobile entered the fray earlier this year with its $50-a-month unlimited plan.