Skype is the most popular application available for making free computer-to-computer phone calls. It also offers very low-cost calling plans that let you make calls from your computer to landlines and mobile phones. It also has great instant messaging and file-transfer features.
Skype was released for the iPhone and iPod touch in late March. Unfortunately, Apple limits Skype and other Voice over IP apps to Wi-Fi connections—you can’t use it with a cellular data connection. Still, if you’re close to a Wi-Fi hotspot, you can use Skype’s iPhone app instead of your voice minutes. And if you have an iPod touch, you’re now able to make calls.
Skype takes advantage of the iPhone’s ability to use filters to sort contacts. You can chat and take a photo from within Skype to use as an avatar image. During Skype calls, you can mute the call, put it on hold, or put it on the speakerphone.