Mac users are like cats - famously contrarian about following the herd. And with the herds rushing to Skype, your typical Mac user will start heading off into some other direction.

London-based Woize (pronounced woy-zee) is targeting this herd of cats with its SIP-based, peer-to-peer VoIP client for Mac OSX, announced yesterday. The company says that the beta version of the software will be released sometime before the end of the year.

The features are pretty comparable to Skype. Calls between Woize users are free, with charges for calls to landline and mobile phones. The company already offers VoIP clients for Windows - including Windows Mobile - and an ATA that lets you use your telephone to make Woize calls.

The main advantage of Woize’s approach is, because it’s SIP-based, Woize users can connect with other SIP users.

“SIP is the not only the future of communications. it is quickly becoming the cornerstone of IP communications as we know it today,” says Erik Lagerway, author of the SIP That and CTO of Shift Networks. “Proprietary solutions are not a viable long term solution and will not impact the future of SIP.”

But Woize is hardly the first one out of the box with a solution to compete with Skype. TelTel of Santa Clara, CA has been offering its SIP-based softphone for over a year now. TelTel claims about two million registered users and is adding about 100,000 users a month, according to CEO Jack Chang.

Sprint Nextel has a secret. You can use Sprint’s high speed wireless data service to make VoIP calls at a fraction of the cost of traditional cell phone calls. But the company isn’t going out of its way to tell you about it.

PeerMe hopes to change that with its new, free service that lets subscribers to Sprint’s mobile broadband make unlimited free VoIP calls between PeerMe users.

And PeerMe isn’t the only player promoting the cellphone as the center of the VoIP universe. This week Cambridge, MA-based iSkoot and UK-based Woize also announced free services for VoIP calling over cell networks.

PeerMe works on any Internet-enabled device from a PC to a mobile phone or PDA – just download the software from the company’s website. The company will also offer a low cost dial-out service, which will be rolled out in the next few weeks. Sprint’s mobile broadband service is $60/month for all-you-can-eat access.

It makes sense to piggyback on the device that’s already in everyone’s pocket.

“If you’re going to use something as your communication hub, you need to have it with you all the time,” says PeerMe founder and CEO Tom Lasater. That role is already filled by cellphones.

Building on the cellphone network also makes sense because WiFi isn’t really ready for prime time, Lassater contends.

Ubiquitous WiFi is “at least three years out,” he says. “Sprint has a few years’ head start.” With Sprint’s network, launched in 2005, subscribers can get high-speed Internet access anywhere. “It’s here, it’s now,” adds Lasater.

The cell phone industry business model is changing, according to Lasater. “The big break was Windows Mobile 5 [operating system for mobile devices],” he says. “This allows anybody to put any software on the mobile phones. Consumers can now download any software. Now you really do have a useful device in your hands.”

While cell carriers worry about cannibalizing their customer base with VoIP services, Lasater thinks they’re short-sighted. VoIP opens up whole new marketing opportunities for selling high-end devices and a one-stop shop for high speed Interent service.

“With unlimited broadband access, you can justify paying for the service,” he explains. “You can justify buying a high-end phone. There are lots of reasons why it would improve [carrier] business. The software is available, anyone can use it, so why not take advantage of it?”