Sprint Nextel has announced its earnings for Q3. The wireless carrier announced small (2%) operating revenue growth to $8.3 billion and less net loss when compared with last year.

The iPhone recently launched on Sprint’s network, and Apple’s handset is admittedly a huge factor for the carrier’s success. Sprint’s wireless customer base had reached a five year high and iPhone owners are considered to be the carrier’s most profitable customers.

Sprint has also said that the iPhone has resulted in the carrier’s best day ever in retail sales:

“The launch of this iconic device resulted in Sprint’s best ever day of sales in retail, web and telesales for a device family in Sprint history. The response to this device by current and new customers has surpassed initial expectations. The iPhone is expected to be accretive for Sprint, and iPhone users are expected to be among Sprint’s most profitable customers.”

Although Sprint’s customer base is growing overall, the carrier saw a slight decrease in new customers in Q3. This is attributed to “customer expectations of a fourth quarter iPhone launch.”

Sprint now offers the iPhone 4S and 8GB iPhone 4 on its CDMA network. Although customers have been complaining about slow data speeds on the Sprint iPhone, the carrier has still sold out of initial iPhone stock and is estimating 1-2 weeks for shipping orders to customers.

Do you think that the iPhone is enough to keep Sprint relevant? Unlimited data does make Sprint an attractive option for new customers, but it’s obvious that all-you-can-eat data won’t be around for long. What will Sprint need to do next to stay above water?