The possible and probable price war among mobile carriers may lead to lower monthly fees for iPhone and other smart phone users.

The hint was first given by analyst Shaw Wu of Kaufman Bros. who said that the difficult economic condition will soon force the second-tier wireless providers like Sprint and T-Mobile to start slashing voice and data fees in order to increase their market share.

Mr. Shaw Wu said that cheaper all-you-can-eat pricing from Sprint and T-Mobile could influence AT&T into slashing its very high fees for iPhone users. Let’s hope so. The iPhone price doesn’t particularly discourage possible customers, but the $70 per month fee surely does.

There are a series of factors that might finally lead to a change as Mr. Shaw Wu suggested.

First of all, pressure from the competition.

Last year, Sprint launched its “Simply Everything” plan,” which offered unlimited voice, data, email, Web, TV, and even GPS for $100 per month. T-Mobile is now testing a $50 to $75 unlimited deal.

This kind of deals may in fact put some amount of pressure on AT&T. However, I wouldn’t bet on it. Apple is directly involved in the monthly fees and it’s surely no known for reducing prices except as a normal part of the technology cycle.

Customers certainly seem to like the all-you-can-eat deals more than the pay-as-you-go plans. Mobile carries might finally take that fact into consideration and, forced by the crumbling economy, might offer more of those deals and stop the rip off already.