Apple allows new versions of several Voice over Internet Protocol services to begin working on its device.
Users of Apple Inc.'s popular iPhone may now be able to save money by making Internet-based phone calls over AT&T Inc.'s cellular network.
Apple this week allowed new versions of several Voice over Internet Protocol services to begin working on the iPhone, according to those services. Previously, iPhone users needed a wireless Internet connection to make such calls, but the change will allow calls from anywhere that receives a strong enough 3G cellular signal.
By using VoIP applications to sidestep the phone's normal calling software, iPhone owners could avoid using up their monthly allocation of minutes from AT&T, potentially allowing them to choose cheaper plans.
A company called iCall Inc. said its app was the first to be approved by Apple. iPhone users can download the app and pay $10 for unlimited phone calls. Or they can choose iCall's free option, in which calls are limited to five minutes and users must listen to advertisements at the beginning of the call.
Calls made over the Internet are sometimes less reliable, depending on the strength of the connection and the quality of the calling service.
AT&T said in October that it had taken steps to allow iPhone users to make VoIP calls over the network, but Apple did not appear to approve those apps until this week.
Apple could not immediately be reached for comment.
Riding the popularity of services such as Skype, Internet telephony has become a fast-growing way for users to make low-cost domestic and international calls.
Skype, which says it often has as many as 20 million users online at once, recently signaled its intention to submit its own 3G VoIP application to the iPhone. "We've got one up our sleeves," the company said this month on its website.