RF.com’s nifty RingFree is a way that you can make VoIP calls on any iPhone, hacked or not. The currently free beta web application uses Safari and AJAX to accomplish the task. Readying your iPhone for use with RingFree is very easy to do and just involves double checking some of your settings through the standard iPhone interface.

The following VoIP service providers have been tested with RingFree:

• Gizmo Project: No limits.
• PhoneGnome: No limits.
• Race Technology: No limits.
• VoicePulse: VoicePulse Access and VoicePulse Connect plans work well with RingFree. The company does not share credentials on its unlimited calling plans.
• Vonage: Only their “soft-phone” product, for which they charge $5 month in addition to their standard monthly service fees.
• Voxalot: No limits.

If you don’t have a VoIP provider never fear you can also use MSN, Yahoo, Skype, GoogleTalk, FWD, SIP URI or your own PBX.

RingFree is currently a free service as they are attempting to monetize it by selling their software to VoIP service providers. Hopefully it will remain free forever.