Fring, the free mobile VoIP service that works just like Skype, is now available for Windows Mobile 5 and Windows Mobile 6 smartphones. Get ready for some free mobile phone calls.

Here is a look at Fring for WinMo smartphones:

Fring allows users to make free VoIP phone calls and conduct multiple live chat sessions through Skype, Google Talk, MSN Messenger, and many other SIP service providers, according to the company.

Fringland says its mobile VoIP client enables "WiFi enabled but SIM-less" Windows Mobile PDAs to function as open VoIP phones, using either WiFi hot spots or 3G cellular data services for access to the Internet. It supports making low cost VoIP calls to PSTN/POTS landline phones using SkypeOut or similar services. "Presence" functions indicate a contact's availability in real-time, allowing the user to select the best calling method based on factors such as the recipient's availability, reception quality, and call cost, according to the company.

For you WinMo users out there curious to check out Fring, you can download the client here.

Back in February I pointed out just how quickly free peer-to-peer VoIP services where moving to smartphones. Yeah, but all those services are for Symbian. So what.

What about Java? Another service, called Vyke, offers a Java-based mobile VoIP, so that base is already covered. And with Fring on WinMo, it's just a matter of time until other free VoIP services are available for any mobile platform.

OK, that's great for consumers. But what about business users? While large enterprises are not likely to adopt services like Fring, you can bet small- and medium-sized businesses will. Speaking from personal experience, when I worked for a small company my colleagues and I all used Skype on our laptops for internal communications, especially when we were on business trips abroad. I can easily see many small business employees also adopting Fring for their Treos.

As for the enterprise, I can easily see vendors currently touting unified communications and Enterprise 2.0 adding P2P VoIP to their platforms pretty soon. After all, P2P VoIP is one of the key apps of Web 2.0. Enterprises are moving rapidly to replicate Web 2.0 flexibility in their organizations. Once vendors add P2P VoIP and presence to corporate desktops, they'll add it to corporate smartphones too.