There is no need to own an iPod or an MP3 player to listen to podcasts if you use UpSnap's free mobile phone based service.

I recently met with UpSnap, the free 411 SMS messaging service which has added a large entertainment service. Through a simple interface users can create a playlist of subscribed podcasts and listen to them through their cell phones.

It's a very large potential user base, there are about 210m SMS capable cell phones in the US. In addition, there is no software download or installation required.

"Podcasts have proved to be very popular, but they have one problem, you need an iPod," said Tony Philipp, CEO of UpSnap. "We've extended the reach of this popular media so that anyone can access podcasts anywhere at anytime using any mobile phone."

The service is free except for a small number of premium podcasts. It is based on a streaming voice technology called SWInG (Streaming Wireless Internet Gateway)from XSVoice - a company it acquired in January 2006. The revenues come from merchants that pay UpSnap on an SMS text-to-call model. A short advert after each podcast enables listeners to connect to merchants.

Once a user has selected their podcasts and they are ready to listen, they text a short one word message to the service which then queues up their podcasts and starts streaming the content.

"The service is for media junkies who want branded content from ESPN, NASCAR, as well as access to niche music, they can have it all on demand on their mobile phone," said Mr Philipp.

It's a clever use of text messaging combined with mobile phone technologies to provide a large library of podcast content, ranging from hip-hop, to technology, to Sunday church sermons. And it frees podcasts from the "pod" and the PC. It essentially transforms a cell phone into a pocket media server.

The UpSnap entertainment service makes use of the spare capacity of the voice networks of the carriers, of which there is a relative abundance compared with their data networks. Since most users have free calling plans at weekends and evenings they don't have to pay a penny to access thousands of podcasts.

Another cool feature of the service is that it allows listeners to send a voicemail to the podcaster--it turns a podcast into a two-way medium.

Web sites with podcasts display a small RSS button that show that their content is available through cell phones. I'd like to try it out next time I'm at SFMOMA, which offers podcasts that guide visitors through its exhibitions.