Analysts will be looking at whether the iPhone is helping Sprint when it reports its first-quarter results Wednesday.
The report from Sprint Nextel Corp., the third-largest wireless carrier in the U.S., will come before the stock market opens.
Sprint has been losing contract-based subscribers for years, but showed a small gain in the fourth quarter, when it started selling the iPhone. The phone is expensive, but Sprint's management considers it essential to competing with AT&T Inc. and Verizon Wireless for high-paying subscribers.
Now, analysts expect it to post another loss of contract-signing subscribers. Estimates of how many vary widely, from 22,000 to 127,000.
Sprint faces multiple long-term challenges. Not only is the iPhone very expensive, it has also embarked on a network upgrade plan that costs billions.