As banks look for ways to get revenue from free services like bill pay, they risk becoming a target of public outcry, as Verizon Wireless has in recent days over a short-lived plan to assess a $2 fee for certain bill payments.

Consumers circulated petitions and organized boycotts over Verizon's fee, which would have applied only to one-time credit and debit card payments made online or by phone (the fee would not have been assessed to consumers who sign up for an automatic recurring payment). On Friday, Verizon said it no longer plans to impose the fee, which was originally set to take effect Jan. 15. The fee was first reported by the blog Droid Life.

Most banks have long abandoned charging for online bill pay, but some have experimented with bringing fees back for specific uses, such as for last-minute payments. The justification for such fees from banks and bill-pay providers is that the price of an expedited payment is more palatable than the late fee and finance charges that would be assessed for missing a due date entirely.

If banks keep their bill-pay fees limited to scenarios such as this one, they may avoid the same outcry Verizon faced, experts say.

"[Banks] really need to be thinking about pricing in a much more holistic way," says Ron Shevlin, a senior analyst at the Aite Group LLC. "It's not just trying to get away [with] charging for something."

Banks are still feeling the sting from Bank of America Corp.'s failed attempt to attach a $5 monthly fee to debit-card use.

"They had to backtrack, and the really negative thing about that is now there is a sense that these were capricious fees," says Shevlin.

Banks may get a better response from consumers if they bundle services under one fee, so that no single service seems overpriced, says Nicole Sturgill, a research director in the retail banking and cards practice at TowerGroup.

"You might get things like identity theft protection, or maybe it comes with a certain number of expedited bill payments, or you get a rewards debit card … You are getting more for what you are paying for," she says.

Expedited bill-pay fees can be justified, experts say, but consumers may demand that other types of payments remain free, even when such services are costly to banks.

"All of these carriers and financial institutions are faced with increased costs and stronger regulations," says Jacob Jegher, a senior analyst within Celent. "They are trying to deal with all that while balancing the customer experience, which is no easy thing to do."