AT&T Inc and network equipment maker Alcatel Lucent have found a software defect that cuts speeds for customers looking to send data from the Apple Inc iPhone 4 or from laptop modems.

AT&T said on Wednesday that the glitch, which Alcatel Lucent is working on fixing, affects less than 2 percent of its wireless customer base as the iPhone 4 is the only smartphone that runs on the network technology in question.

The glitch is the latest technical embarrassment for AT&T, the exclusive U.S. provider for iPhone. It was previously hit with online problems for ordering the phone.

Last week Apple had also admitted to a technical problem with its signal strength display on the iPhone 4.

Mark Siegel a spokesman for the No. 2 U.S. mobile service provider said the latest problem only affects devices using a high-speed data technology known as 3G HSUPA in AT&T markets that depend on Alcatel Lucent network equipment.

He said that AT&T is still supporting data services in these markets but noted that the speed at which a consumer can send data such as emails has been cut to a maximum of 384 kilobits per second from a potential maximum of 5.67 gigabits per second, Siegel said.

He said that speeds of data downloads, the speed at which data such as Web pages are sent to a phone, were not affected in those markets. He did not have an estimated time for when the glitch might be fixed.

Siegel said many of AT&T's laptop modems run the HSUPA technology.

Alcatel Lucent expects to fix the problem fairly soon without having to visit the cellular towers where the equipment is held, Alcatel Lucent spokeswoman Mary Ward said, but did not give a more specific time frame.

The problem surfaced after the launch of iPhone 4 because of a big increase in data usage. But she said the problem is not with the iPhone 4 itself and is not affecting other carriers besides AT&T.

(Reporting by Sinead Carew; editing by Derek Caney)

Ios Apple inc. Iphone