Viber - Free Phone Calls is an iPhone application that lets you make free phone calls to other iPhone users that have Viber installed. When you use Viber, your phone calls to any other Viber user are free, and the sound quality is much better than a regular call. You can call any Viber user, anywhere in the world, for free
Skype gives you free calls and instant messages to anyone else on Skype. You can also call landlines and mobiles and send SMS anywhere in the world, at great rates. Skype is free to download and easy to use.
Free Skype-to-Skype calls
With Skype on your iPhone or iPod touch, simply sign into Skype from any WiFi zone, and call friends and family on Skype totally free
Media5-fone for iPhone - The Media5-fone is a softphone application for iPhone, iPod Touch and iPad. It is a SIP Client which enables users to make and receive VoIP calls. VoIP calls are calls established over a Wi-Fi or 3G connection using the IP technology of the Media5-fone
Talk, chat & tweet on fring and other favorite social services including Skype, MSN Messenger, GoogleTalk, Twitter, Yahoo!, ICQ, AIM, all through one central profile, using your iPhone and iPod touch's internet capability
WePhone - WePhone allows you to make low-cost international phone calls with crystal clear sound quality. The app supports phone call recording and caller ID display.
· VERY VERY EASY TO USE!! Use it exactly the same way you use embedded Apple Phone app for iPhone. You can start making call just after download with auto assigned account and initial $0
Access your Google Voice account right from your iPhone.
Receive push notifications for new text or voicemail messages.
Send free text messages to U.S. numbers and make international calls at cheap rates.
Listen to your voicemail, read transcripts and manage your Google Voice inbox.
Display your Google Voice number as caller ID when making calls
FriendCaller Instant VoIP - Free VoIP calls and low cost phone calls. Other VoIP apps require both parties to download the same app, register and exchanging their user IDs before you can talk free to each other, not FriendCaller. FriendCaller provides instant VoIP.
FriendCaller provides free calls and instant messages to anyone else on the Internet
Google Voice (iPhone) - Access your Google Voice account right from your iPhone.
Receive push notifications for new text or voicemail messages.
Send free text messages to U.S. numbers and make international calls at cheap rates.
Listen to your voicemail, read transcripts and manage your Google Voice inbox.
Display your Google Voice number as caller ID when making calls
Bria iPhone Edition - CounterPath, the market leader of desktop and mobile VoIP software products and solutions, brings you Bria, iPhone Edition. Bria is an open standards, SIP-based softphone for the iPhone and iPod touch.
Bria iPhone enables you to securely connect and communicate easily and efficiently whether for business or personal use
Rynga for iPhone - Rynga allows you to make cheap calls from your mobile phone. The app uses your phone's wireless connection to place the call instead of your plan minutes, saving on costs. Calls to other Rynga users are free.
Rynga works anywhere there is a WiFi, 3G or GPRS connection available