The age-old annoyance of being a dime shy of buying a mid-afternoon snack may soon be over if a new Isis initiative takes hold across the country.

The joint-venture mobile payment app took another baby step towards ubiquitous use Monday as it announced it may be accepted by up to 7,500 vending machine in its trial markets.

Backed by T-Mobile, AT&T and Verizon Wireless, Isis launched a trial of its service at the end of October in test cities Austin, Texas and Salt Lake City.

Now, Isis is partnering with USA Technologies (USAT), which specializes in cashless payment systems, to launch NFC-enabled vending machines, allowing users to buy items by simply tapping their phones instead of inserting cash.

The mobile wallet march

Though by no means everywhere (two cities is hardly taking the country by storm), the mobile wallet scene is slowly starting to take shape in the U.S.

"By working with USAT, we look forward to expanding the growing list of places where consumers can use the Isis Mobile Wallet," Jim Stapleton, Isis's chief sales officer, said in the press release.

The launch isn't without its hangups: there is no telling how many vending machines will end up accepting Isis, or when those machines will hit street corners. Individual vending machine owners will have to elect to get Isis compatibility.

While this might not seem like the most Earth shattering news, any movement in the NFC-based payment game causes tremors in that space, especially when competitors to Google Wallet are taking noticeable strides.

Which will come first?

Right now the mobile payment industry faces a chicken and egg problem: businesses don't want to invest in new payment infrastructures unless its popular with customers. But it won't gain traction with consumers until they see a large infrastructure to justify using a new payment method.

The industry's biggest challenge right now is trying to get the momentum to gain widespread acceptance. This announcement is aimed to help the industry get to that tipping point.

"We also believe that our work with Isis sends a clear message to vending companies in these two cities -and to the broader market we serve - that there is tremendous opportunity in cashless adoption," USAT's CEO Stephen Herbert said in the release.

Though digital wallets are still new, the various apps and services have a good foothold to start with. Isis alone can be used at McDonald's, Rite Aid, 7-Eleven, Petco and other businesses in its test cities.

Isis also works with major credit cards such as American Express, Capital One and Chase.

A tortoise race

But if Isis is to become ubiquitous, it still has a few hurdles. The biggest is that the service is only supported by a few Android phones, such as the Droid Incredible 4G LTE, Droid Razr HD and Droid Razr Maxx HD. And to use Isis, consumers need to obtain special secure element SIM card from carriers.

It does appear that Isis is making its way onto more and more phones. According to Isis' chief marketing officer, it should be on about 20 phones by the end of the year.

If Isis and other NFC-based payment systems are going to find a place in consumers' wallets, it seems like it will be a slow crawl to the finish line, though one that can now be fueled by vending machine staples.