NEW YORK (

TheStreet

-- Americans are slow to change the way they pay their bills but a recent report by Aite Group determined that mobile bill payments are expected to rise 376% over the next three years.

People that pay bills through the mail or in-person are expected to experience a decline in volume of roughly 6%. Mail bill pay volume is estimated to drop from 4.9 billion in 2010 to 4.6 billion in 2013, while the volume of mobile payments is projected to grow to more than 43 million units to 207 million units.

The method of payment will change as well. Paying bills by check is estimated to drop from 37% to 33%. Cash is expected to drop 4% and money orders are projected to decline by 7%.

Aite Group acknowledges that consumers do not like to change their ways when it comes to bill paying, with 70% of the people surveyed as having not changed anything about their bill paying in the last 2 years.

The explosive adoption of smart phones is expected to be a big driver for people to move to mobile bill pay. Roughly 50% of the overall population will be smart phone users in the next few years.

These users are expected to mirror their bill payments with increased use of the phone. This seismic change in the way Americans pay their bills has created an opportunity for several companies to try to become the mobile bill payment company of choice.

PayPal

, a division of

eBay

(EBAY) - Get Report

claims to have been delivering mobile payments since 2005. PayPal transacted $141 million in mobile payments in 2009 and expects the number to climb to $700 million in 2010.

The quest to own the mobile bill pay market hasn't come without difficulties. An audit by viaForensics discovered security holes in PayPal's iPhone application, and the company is rushing to create a software patch to fix the problem.

To be fair, viaForensics founder Andrew Hoog told the Web site Threatpost that other mobile payment applications had similar flaws. PayPal is one of the few companies willing to publish its volume data, leaving other to wonder just how much business the competitors are actually handling.

Boku

is a private company financed by private equity firms like Benchmark Capital and Khosla Ventures. Boku earns between 5-10% of the transaction amount as a fee so the higher the transaction amount, the better it is for Boku.

The company just announced a trial with

AT&T

(T) - Get Report

, similar to a recent deal it struck with

Vodafone

(VOD) - Get Report

a few weeks ago.

Facebook also just announced it's going to test Boku as a payments system as an alternative to competitor Zong. Boku has raised more than $40 million and insists it wants to remain independent. However, rumors have cropped up that

Apple

(AAPL) - Get Report

or even

Google

(GOOG) - Get Report

are talking with Boku, but for now it's just talk.

Apple is awash in cash and a rumored nine-figure acquisition offer would still be chump change for the company.

Zong

is also a private company and like Boku, is also doing a trial with AT&T. Maybe AT&T wants to make sure its backing every horse? Also like Boku, Zong's technology sends the purchase through a user's mobile phone number.

Zong claims to be the leading mobile payment platform for sellers of digital goods and services, reaching over 2 billion users. Zong, though has only raised $15 million, way behind Boku.

Investors include Echovox, Matrix Partners and Advent Venture Partners. Zong offers Android developers an in-app purchasing tool. Developers have been slow to write for Android finding it harder to monetize than with the iPhone which has had in-app purchases for more than a year.

Obopay's

got some big names backing it, including Alliance Bernstein,

Nokia

(NOK) - Get Report

and

Qualcomm

(QCOM) - Get Report

.

Obopay has raised $69 million from private equity and then another $35 million from Nokia. Its latest entry is its new Mobile Money for Banks product, which gives banks the ability to deploy branded mobile payment offerings to customers, essentially providing banks an easy solution to mobile bill payment.

However,

Citigroup

(C) - Get Report

earlier this year shut down its program with Obopay. It believes customers are years away from adopting mobile payments.

Citi says it's still committed to the technology but no longer active in the trial program. Obopay doesn't release number of users or volume data citing its privacy requirements by Citigroup and

MasterCard

(MA) - Get Report

.

MoPay

is the mobile payment unit of Mindmatics with T-Venture Mobile as one of its investors. MoPay also calls itself a global leader in the space. Its focus is on social gaming payments.

MoPay claims it was the first provider to enable mobile payments for the purchase of physical goods around the world. It may be the global aspect that differentiates it from Boku and Zong, which are based in the United States. MoPay connects its platform to 80 countries most recently adding India and South Korea.

--Written by Debra Borchardt in New York.

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