Napster’s recently revealed plan to extend its music service to mobile phones has a long way to go before cells become iPod killers.

On Wednesday, Napster and Swedish phone giant Ericsson announced a deal to develop the first digital music service for cell phones. The service will launch sometime in the next year.

But even as cell phones are increasingly tricked out with MP3 players, television and games, analysts said it’s unlikely people will rush to replace their iPods with music-playing cell phones.

“We don’t see this as a displacement any more than digital cameras were displaced by camera phones,” said Michael Gartenberg, research director with Jupiter Research. “As long as music phones command a significant premium over regular phones then it’s going to be difficult to see how the consumer will embrace them.”

Susan Kevorkian, an analyst with IDC, said there are some consumers who want to load their phones up with features like music, games and video, but plenty of others still prefer devices like the iPod that do one thing, and do it well.

“We think there’s going to be a very large middle area where people will use both types of devices,” she said.

Some phones already have built-in MP3 players so people can take a portion of their music collection with them. Napster’s mobile music service for the phone will work like Napster To Go: Subscribers will be able to synch their phones with their PCs and fill up, or “sideload,” the phones with tunes.

But there are still a number of hurdles to overcome for music on cell phones to be seamless for customers to use, experts said.

In Napster’s case, if the phone is not compatible with the PC (making users unable to sideload the phone), users must purchase songs a la carte and download them wirelessly to their phones — even if they are Napster subscribers paying the service’s $15 monthly fee. A copy of a purchased song is then e-mailed to the user’s account so it can be stored on the individual’s PC as well, said Brad Duea, Napster president.

IDC’s Kevorkian said there may also be problems with competing formats for wireless downloads. Customers might purchase a download for their phone, but they may not be able to play it on another MP3 player. Also, the interfaces for digital music services will need to be adapted for phones, which are much smaller and designed primarily to make phone calls.

And in some cases, cell phones just aren’t ideal for music.

More here.