Last week Kaufman Bros. analyst Shaw Wu suggested that AT&T should revisit its current data plan options for the iPhone to keep it competitive in the tough economic climate. Now, it seems that recent moves by rival carriers to lower prices put additional pressure on AT&T to do the same, according to Wu's latest report to investors.

The complaint about high prices for the iPhone aren't usually centered on the $199 (heavily subsidized) purchase price, but the high monthly fees AT&T charges for voice and data options. Wu, among others, has suggested that AT&T consider additional pricing tiers in addition to the $30 per month unlimited data plan, which is currently the only option for the iPhone. Along with a $40 per month minimum voice plan, and taxes and fees, iPhone users are seeing monthly bills that start at about $75 and go up to $150 for unlimited voice, data, and text messages.

Recent pricing options from rival carriers are much lower. SprintNextel offers its "Simply Everything" $99 per month unlimited plan, and even its "Everything Data" plan for 450 peak voice minutes includes unlimited data and text messages for $70. SprintNextel's Boost Mobile subsidiary is offering a new $50 a month plan that includes unlimited talk, messaging, Web, and walkie-talkie service. And T-mobile is currently testing a plan that would offer unlimited voice and data for $75 per month.

Wu believes the lower prices will keep smartphone adoption rates up, and if AT&T were to follow suit, it would be a further boost to iPhone sales. "Overall," Wu wrote in his report, "we view lower service plan prices as positive as it should help smart phone adoption maintain its healthy pace, even in this fragile economy." We can't deny that it seems wise for AT&T to explore this path.