In today's Wall Street Journal, Li Yuan writes: "... Entering the entertainment business is proving tricky for Sprint and other U.S. cellphone operators. With most American adults already users of cellphones, the wireless industry needs to reap higher monthly fees from existing customers to grow. Persuading them to pay extra for music, videos and other entertainment and information over their phones is considered essential, and the industry has poured billions of dollars into the initiative. ...¶... Before they could begin offering entertainment, the companies first had to upgrade their infrastructures. Sprint says it has spent more than $1 billion on its network so that it could handle data-heavy content and it will have to spend more to make it available nationwide. Yet only 250,000 of its 47.5 billion customers have phones capable of operating on its new network, the company says. Link: Wall Street Journal (paid access only -- or get it off the newsstand).