Process Credit Cards Anywhere: 5 Smartphone Tools Mobile-payment hardware lets your business accept credit cards through an iPhone, an Android handset or another smartphone.

Whether you work as an in-home massage therapist, operate a taco truck, or run some other small business, you're missing sales if you can't process credit cards. However, a number of mobile payment tools now let you accept credit cards on an iPhone, an Android handset, a Windows Phone, or a dumber handset. You just need to sign up, attach credit card reader hardware, and navigate the fees.

Most of these tools require a merchant account. Banks regard credit card transactions similar to the way they do loans: Since they're afraid that you'll run up a bunch of sales with fraudulent cards, pocket the money, and book a flight to Bermuda before they catch on, they're stingy about granting access. You'll have to pass a credit check to earn a bank's trust and a merchant account.

Depending on the credit card tool, you'll pay a recurring fee for your merchant account, a percentage of each transaction, a flat fee per transaction, initial hardware costs, and possibly an additional monthly fee. This framework makes sense for businesses that process a lot of sales, keeping individual transaction fees low. But a wild-card service -- Square -- eliminates that monthly overhead, instead charging more per transaction.

We looked at five mobile devices and apps that enable small businesses to process credit card transactions. All provide the same basic functionality, but only some will match your specific needs.

RoamData RoamPay

Pros: Works with more than 200 devices; includes many crucial transaction features and helpful extras

Cons: Weak interface cribs from ten-year-old, "dumb" phone designs

Roam Data's RoamPay distinguishes itself by its versatility. In addition to offering apps for iPhone, Android, and BlackBerry, the device works with more than 200 other handsets. Since it simply plugs in via the microphone jack, you can run credit card transactions on a Motorola Razr, a Palm Treo, and many more phones.

Unfortunately, the app-based, smartphone RoamPay interface seems merely scaled up from dumb-handset navigation. For example, it presents a numbered list of options on each page instead of buttons, and you need to tap twice to make selections. Instead of the credit card swiper automatically turning on, you have to press a button to activate it each time, and if you use too much force -- as we often did -- you can wind up bending the hardware into the iPhone's sleep button, KO-ing your POS.

The RoamPay software (or Website portal on app-free handsets) turns the audio from the swiper into credit card details. Data is encrypted in the hardware itself, then encrypted again on the phone before transmitting through your Internet connection. Get past the lousy interface, and the process works well, including some crucial features that others can miss, such as the capability to store transactions offline if your service is interrupted.

RoamPay is full of extras, such as a Web portal (for Mac or PC) where you can manually enter transactions. Although the device and app fundamentally work, we wish Roam Data had put more effort into the basic design before adding fancy features.

The costs for RoamPay vary depending on where you buy it. One company, ACT Merchant Services, charges $150 per year, 1.95 percent per transaction, and $45 for the RoamPay hardware.

Square

Pros: Simple setup process; free hardware and no monthly costs

Cons: Pricey for higher-volume businesses; lacks professional features

Square positions itself as the PayPal of mobile credit card transactions; it's simple, easy, and suitable for sole proprietors with occasional sales. The service charges a rate of 2.75 percent plus 15 cents per credit card transaction, with no hardware or monthly costs. If your business runs credit cards daily, you'll find a better deal with a competing service that adds in those costs but bills less per transaction.

Unlike other services, Square requires no merchant account. After Square verifies your identity by way of your Social Security number and other personal data, it sends you the free credit card reader. Getting started is easy, but if you make a mistake with the identity check -- we mixed up "north" and "south" on an old address -- you don't get a second chance. (You'll have to contact customer service for help.)

The Square app for iPhone and Android takes a simple approach to processing transactions. You plug the tiny reader into the headphone jack, key in a price, and start swiping. Just be sure to turn up the volume with this and other audio-based readers; it won't work if left quiet.

Note, however, that Square lacks features that can be important for many businesses. For instance, you can't refund or void transactions from the device; you have to do so with a computer and Web browser. And you can't store transactions offline if you lose the signal. Such omissions are just additional reminders that Square could be great for a part-time babysitter or artist, but weak for restaurants, street vendors, and other bigger businesses.

Intuit GoPayment

Pros: Simple interface streamlines transactions; list-based system lets you tap regularly purchased items instead of manually entering numbers

Cons: Lacks complete features of some competitors, such as an offline mode and older returns

Intuit's GoPayment doesn't require -- or include -- a credit card swiper, as it allows you to manually enter numbers through any Internet-connected phone. But most businesses will want the convenience and lower fees of a card reader; we tested the Mophie Marketplace Credit Card Reader ($180) on an iPhone 3G, and the Bluetooth Card Reader ($150) with the Motorola Droid X. To protect each transaction, those card readers encrypt data before sending it to the phone.

GoPayment costs $13 per month, 30 cents per transaction, and 1.7 percent for swiped charges. (Manually entered card numbers cost 2.7 percent.)

Since Select the items in your transaction, and then tap Create Order to quickly process a customer with Intuit GoPayment.GoPayment can accept multiple logins, several of your employees can run transactions; most other services force you to share a single account login. And since it's from Intuit, GoPayment also interacts with QuickBooks, sending that program your sales data.

GoPayment easily processes transactions. In most cases, the interface gets you in and out quickly, although Intuit could streamline it further. Unlike most competitors, it gives you the option to assemble a price list of your inventory and then just tap items to create orders; the process, if it matches your needs, will speed up transactions.

In GoPayment you'll find other crucial basics, too, such as the ability to void recent charges; it can e-mail a receipt to a customer, as well. The Mophie card-reader encases an iPhone 3G or 3GS but helpfully includes a micro-USB port so that you can still sync and charge the phone with it attached. (No iPhone 4 support is available yet.)

Even though GoPayment lacks a few features, such as an offline mode and refunds of older charges (you'll have to use a computer and Web browser for returns), it can reliably process business transactions. It's a solid choice that's ideal for businesses with a fixed price list.

PhoneTransact iMerchant Pro

Pros: Requires a password to open the app; simple interface gets you through transactions quickly

Cons: Graph function lacks practical value; can't store offline transactions yet

iMerchant Pro tries to enliven your transactions with its clip-art-like interface and optional sound effects. Finish a sale, and you'll hear the classic cash register "ka-ching." Although these and other features clearly can't beat those of competitors, iMerchant Pro includes a surprisingly rare bonus: password protection. You can't launch this iPhone app without entering your personal password -- a simple, thoughtful security precaution.

Security is solid elsewhere, too. The hardware encrypts the card data before passing it to your phone, so the information stays safe.

iMerchant Pro software costs just $1 on the iPhone, and the credit card swiper costs $100. (New customers can get $50 off that price.) You pay 1.69 percent and 24 cents for each swiped transaction. The service requires a gateway and merchant account; you can use your own merchant account, or pay about $34 per month for both. The fees enable useful functions, including QuickBooks export.

The hardware latches onto an iPhone 3G or 3GS dock connection. However, unlike some devices, it omits a pass-through USB port for charging your phone or connecting to iTunes while it's attached.

The software is sufficient but imperfect. You can send receipts, void transactions, give credit refunds, and perform other basics. But some extras are just confusing, such as graphing transactions by credit card type into a pie chart. Sure, you can see the percentage of Visa to MasterCard transactions at a glance, but the feature just makes us want more-comprehensive sales reports. Why not chart the percentage of out-of-state visitors, high-sale transactions, sales by time of day, or other data useful to a business?

The app also can't store offline transactions and upload them later. That feature is coming soon, but for now you'll have to be certain that your Internet connection will hold up.

iMerchant Pro solidly performs its credit card transaction duties. Some features, such as password protection, add value -- but others, like the graphing, feel like placeholders for app updates.

PayWare Mobile

Pros: Elegant swiper hardware includes stylus; reports page lists more details than most rivals

Cons: Awkward interface has glitches and inconsistencies

Get past the unintuitive, sometimes buggy PayWare Mobile interface, and you'll discover a solid foundation for business transactions. It's too bad that you have to fight to find the good parts of this iPhone credit card processor.

PayWare Mobile's main screen is streamlined to let you enter a transaction amount, swipe a card, and process a payment. But the interface weaknesses appear immediately. Does the big Manual Entry (or Slide Card) button mean that you're currently in manual (or card-reader) mode? It's the opposite of what we thought. Parts of the interface occasionally stopped responding to our touch, keeping us from tapping the cost field, for instance, or swapping the manual and swipe modes. Corner buttons sometimes change name within the same screen. The interface feels barely tested.

Although the software seems clunky, the hardware is surprisingly sleek. Blue-arrow lights identify the direction to swipe the card. A mini-USB port lets you charge, but it can't dock. An iPhone-savvy stylus hides inside the device, letting customers sign with the pointer instead of a fingertip. And the hardware encrypts data before it passes through the iPhone, protecting the information.

Considering the ho-hum interface, we were surprised by the attention to detail in the transaction reports. You can pull up lists of sales and even search for a certain one. Even though you can't run comprehensive reports, such as comparing sales between Mondays and Fridays over time, PayWare Mobile includes more data than most competitors do.

You'll find PayWare Mobile sold through merchant providers, such as iPhone Merchants. That company charges $20 per month plus 1.59 percent and 25 cents per transaction, as well as a $45 setup fee and $115 for the hardware.

PayWare Mobile needs improvement. While its basic functionality matches -- and sometimes exceeds -- that of competitors, its awkward, glitch-prone interface isn't worth the trouble.

The Verdict
You'll have to crunch the numbers and assess your own needs to decide which up-front fees balance out lower per-transaction fees -- maybe your volume justifies such rates. Those costs aside, the right choice should match your business.

We like GoPayment's price-menu system for businesses with a small, fixed inventory. Otherwise, RoamPay's great features just barely lift it above its weak interface. For smaller businesses that don't want a merchant account and sell at low volumes, Square stands alone.