Ringfree Mobility is seeking a round of funding to expand its mobile Internet voice calling solution for smart phones including the iPhone.

The company is entering a crowded space, as Matt Marshall wrote last week in a profile of a couple of competitors, Fring and Nimbuzz. But Ringfree Mobility believes it has a user-friendly solution.

The San Francisco company began beta testing its RF Dialer application in February. Like other voice-over-Internet-protocol services (VoIP), RF Dialer and its backend service, RF.com, enables cell phone users to make cheap international calls for pennies a minute. No software installation is required. The company’s motto is “call everywhere from anywhere with no hassle.”

The company believes it has simplified the process of using an iPhone or other smart phones. You sign up on its web site and can start making calls within a minute. You then put the web page icon for RF.com on the iPhone’s main screen. To make a call with an iPhone, a user clicks on an RF.com icon. A dial pad pops up. The user can select the type of call to be made from a pull down menu, with choices including Skype calls.

Here’s where it’s different. The choices on the menu also include GoogleTalk, YahooTalk, MSN Messenger, AIM, VOIP services such as Vonage or Gizmo, or an office phone system such as Asterisk. The RF Dialer is like a replacement for the iPhone’s built-in dialing application. Ringfree Mobility is not a phone company itself and so you can use any calling service you want with it. It doesn’t compete with the mobile carriers, and it also doesn’t compete with the VoIP service providers.

If the user selects the Skype service on the menu, then the user uses the iPhone keypad to type in the name of the person being called. Then the user clicks on the call button. The iPhone then makes a local cell phone call over the AT&T network to the RF.com media gateway. The gateway then goes out over the Internet and connects to the Skype service, which then connects the call to the person being called. RF.com reserves the data channel of the iPhone to find out pertinent facts such as which friends are online.

By contrast, other mobile VoIP services such as Fring bypass the cellular network and use the data channel to make an Internet call. But the quality of these voice calls is often poor, given spotty access to Wi-Fi networks needed to complete the connection.

Like Mig33 or iSkoot, RF.com works in tandem with — and not in competition to — mobile carriers such as AT&T since it generates voice calls on the carrier’s network. iSkoot, however, is Skype only, while Mig33 is a VoIP service provider.

Competitors include Hipsip, which we wrote about in April. Hipsip, which works only with Skype, can make Skype calls but for now requires that a user’s own computer running the Hipsip software be up and running in order for the calls to go through. Other rivals include Mobivox and Talkety.

The RF Dialer is available for the iPhone in beta mode and founder Marcelo Rodriguez (pictured below, right) says it works entirely within Apple’s permitted use guidelines. It is easily transportable to other web-based phones including those from Nokia, Samsung, LG, and Google’s upcoming Android mobile platform. PhoneGnome has already licensed the RF.com technology and a second major VOIP partner will be announced soon.

Ringfree Mobility is still exploring different business models, such as offering premium services or partnering with other VOIP service providers such as PhoneGnome.

Rodriguez was formerly CEO of VoIP news site Voxilla.com and managing editor of Miami Herald New Media. His cofounder is Eric Chamberlain (left), former chief technology officer at Voxilla. They formally incorporated the company in March, 2008. The company has four employees and has been self-funded to date.

[Disclosures: Rodriguez was an editor at the San Jose Mercury News years ago and occasionally edited stories I wrote when I worked there. He is married to Katherine Fong, a San Jose Mercury News deputy managing editor who is in charge of online journalism at the newspaper.]

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