Sprint Corp., owner of the fourth- largest U.S. wireless-phone service, said it will offer partial refunds to new corporate customers for poor call service.

New wireless contracts will promise refunds of as much as 30 percent to corporate customers if Sprint’s nationwide network has too many dropped or failed calls during a month, the Overland Park, Kansas-based company said in a statement. Customers must use a Web site to monitor Sprint’s performance.

Sprint is the first U.S. wireless carrier to give a service guarantee to all of its business customers, said Eugene Signorini, an analyst at Boston-based researcher Yankee Group. The move will help Sprint, which Consumer Reports magazine last year ranked near the bottom among U.S. carriers for service performance, improve the reputation of its network quality.

``It indicates that Sprint is serious about delivering enterprise-class wireless offerings,’’ Signorini said. ``Sprint, by being the leader out there, will also be able to set the bar where they want it to be.’’

Customers can request a 10 percent refund of monthly charges for each of three problems: if more than 2 percent of calls made within Sprint’s coverage area don’t connect; if more than 2 percent of completed calls are involuntarily disconnected; and if Sprint’s network is not running 99.9 percent of the time.

Shares of Sprint rose 10 cents to $18.08 in New York Stock Exchange composite trading Friday. The shares have risen 10 percent this year.

Network Performance

The measures are based on the performance of Sprint’s nationwide network, not on any one customer’s experience, said Vicki Warker, a vice president in Sprint’s business solutions unit. Customers can check a Web site each month to view Sprint’s network performance and request a refund if it failed.

``Business customers would prefer that we have a high- quality network than to get their money back,’’ Warker said.

Sprint’s PCS wireless unit had the second-highest number of complaints per subscriber among the six-largest U.S. wireless carriers last year, according to U. S. Federal Communications Commission figures compiled by Consumers Union, which publishes Consumer Reports magazine. AT&T Wireless Services Inc. had the most.

Sprint ranked lowest or second-lowest in terms of customer satisfaction in 10 of 12 U.S. cities, according to a survey of 31,000 subscribers conducted last year by Consumer Reports.

Sprint said it spent $667 million during the second quarter to improve call quality on its wireless network, a 25 percent increase in spending from a year earlier.

Revenue in the PCS wireless unit, which accounts for more than half of Sprint’s sales, rose 17 percent to $3.61 billion as Sprint added 897,000 wireless subscribers in the quarter. Its long-distance revenue declined 6.6 percent to $1.87 billion.