For a handful of pioneers, the mobile payments revolution needn't wait for questions about hardware to be resolved. Not when so much is possible with software innovations on existing phones.

Most companies agree that embedding a near-field communication chip in mobile phones is the endgame, but it may be a few years before such devices are widely used. There are still questions about who owns the customer relationships, and introducing new phone hardware will take time as well.

Meanwhile, much of the software infrastructure needed to create a so-called mobile wallet is already available.

"There's a whole other side to the NFC chip" beyond what the hardware can do, said Drew Sievers, chief executive and co-founder of mFoundry Inc. in Larkspur, Calif.

Starbucks Corp. uses software from mFoundry for its mobile app, which displays a bar code to make payments — users hold the phone's screen in front of a special reader, much as they would hold an NFC-equipped phone over a reader at the point of sale once such hardware becomes commonplace.

The Seattle coffee retailer said the true value of its mobile app is not how customers use the phone at the point of sale, but in how they use the phone before they even get to the cash register.

Many shoppers prolong their time at checkout by reloading their prepaid Starbucks cards, slowing down the line of other customers. Since the mobile app lets users check their balances, and if necessary reload the card, at any time, they can do it while they wait in the queue.

"The problem they had to solve was how do we let people reload without disrupting the line," Sievers said.

Chuck Davidson, the category manager for innovation on Starbucks' card team, said through a spokeswoman that "this gives our customers another way to reload their Starbucks card that's fast and convenient."

Shopkick, of Palo Alto, Calif., has also been exploring the potential of software rather than wait for changes in phone hardware.

Its app, available on Apple Inc.'s iPhone and mobile phones using Google Inc.'s Android operating system, lets consumers earn rewards points for walking into retail locations of Target Corp., Macy's Inc., Best Buy Co. Inc. and other participating merchants. Users can also scan bar codes in dressing rooms and tags on specific products to earn further rewards.

Consumers can use the points they earn — called kickbucks — toward gift cards at the merchants.

Adding NFC, which allows for two-way communication between a device and a reader, could make a program like shopkick more applicable to banks or other companies with payments products, said Richard Crone, the chief executive of Crone Consulting LLC in San Carlos, Calif.

For example, a retailer or a bank could let a consumer register a payment card with the app, allowing him or her to use the app to pay for transactions at the point of sale. Enabling a consumer to also see the balance of funds or available credit on the registered card within the app could further increase usage of that card.

"If I'm a retailer and provide the balance for my store credit card but I don't provide the balance information for bank-branded payment types, then they already have a built-in advantage that will help steer the customer," Crone said.

Alternatively, a bank could nudge a consumer to use its card, generating interchange revenue for the issuer, he said.

AT&T Inc., Verizon Wireless and T-Mobile USA formally announced a mobile payments joint venture this month. The venture is developing a system called Isis that would run transactions over Discover Financial Services' network. In addition to allowing a consumer to use NFC-enabled phones to pay for transactions, the technology could also store coupons and loyalty and other nonpayment accounts on their devices.

"This is a commerce network, not just a payments network," said Michael Abbott, the joint venture's chief executive.

"It's not just a card on a phone," he said. "There are a lot more opportunities at the end of the day for banks on the top line through that commerce."

Transactis Inc., an electronic billing software company that bought the mobile couponing startup OfferIQ in August, said it sees new ventures such as Isis as another payment mechanism to connect to its software.

The New York company is testing a system that allows consumers to receive alerts by text message, e-mail and Facebook Inc.'s social networking website about coupons and other deals in their area.

Transactis also is partnering with banks, which will make it possible to receive alerts through existing mobile applications.

Consumers redeem the rewards by using a payment card they have registered with the program. They receive the discount as an automated clearing house deposit into their checking accounts or as a printed check in the mail, said Josh Kampel, the chief marketing officer for Transactis.

Users who sign up through a participating bank can also receive the rewards as a statement credit.

Transactis has announced an agreement with JPMorgan Chase & Co.'s merchant acquirer, Chase Paymentech Solutions LLC, to market the service to retailers and has agreements with others, Kampel said. It also is working with the TD Retail Card Services division of Toronto-Dominion Bank, and other issuers.

"Our idea was to be able to attach these incentives to any form of payment," including alternative options like the nascent Isis network, Kampel said.

Visa Inc. also has stressed the ability to do more than just payments in trials it is conducting with Bank of America Corp., JPMorgan Chase, Wells Fargo & Co. and U.S. Bancorp.

Those companies are testing microSD cards containing payment card information. Consumers can install microSD cards in many mobile phones by themselves.

"When we look at mobile payments evolving in the U.S. or other places it really is going to have to be an open wallet," said Bill Gajda, Visa's global head of mobile. "It won't be just a Visa payment card. It could be a loyalty card [or] some kind of card that captures coupons."

"We think that they should be able to put whatever they want on that wallet," Gajda added.

For banks, the real concern is not which hardware will prevail but who controls the use of ancillary software programs.

"The one who enrolls the customer with a check-in service is the one who controls the interaction," Crone said.

"Right now it's … a run for the roses to figure out what's the best way to check customers in," he said. "If retailers or banks or third parties were to wait for NFC, they might not get a leg up for enrolling customers, because it's not in the phones as of yet."