One of the biggest grumbles about buying through mobile devices is the checkout process. For multichannel retailers, the solution is close to home.

Time and time again, consumers – and even some retailers – are incredulous that someone would buy over the mobile phone, going through the laborious process of entering the credit card number and expiration date on a small screen.

Another issue that the skeptics bring up is quite reasonable to ask: what if the line drops? What happens to the transaction?

Those doubts are valid. Indeed, the first is easily tackled.

Integrated checkout
For those who follow the industry, the growth of smartphones has been the consumer-electronics success story of this new century. By some estimates, one out of two mobile phones in circulation by 2013 are expected to be smartphones.

And what smartphones do best is improve the user experience with bigger screens and more functionality. Mobile commerce will be the biggest beneficiary of these new smartphones which, if looked at closely, are more akin to mobile computers.

Typing credit card details on an Apple iPhone, Motorola Droid or a Google Nexus One is that difficult. Yet, it does not compare with the ease of transacting on a computer-based ecommerce site.

Which is why the Amazon model is one to follow.

The world’s largest online retailer – if Dell is not counted – Amazon has a remarkably simple killer tool: the one-click checkout. And that ease of checkout, plus the intuitive recommendations, sophisticated search engine, smart merchandising and deep inventory, have garnered 93 million customers for Amazon – almost one out of three U.S. consumers.

Amazon stands tall
Shopping on an Amazon mobile site is incredibly easy.

While the iPhone experience is probably the best, shopping on the Amazon BlackBerry site is equally easy. Type in a book or CD title or television brand’s in the search box on the opening screen and a bunch of results pop up. The results page is clean and the items easily clickable.

Once the item is placed in the shopping basket, the consumer can continue shopping or head to checkout. At checkout, the email address and password are asked to generate a page showing the last four digits of the credit card on file and the expiration date. Consumers can either enter a new shipping address or opt to send to one on file.

Once these choices are made, the consumer clicks on the checkout button and the transaction is completed.

What Amazon has done is tied its ecommerce engine to its mobile commerce operations. That is something all retailers can – and should do – to enable easier transactions on their mobile sites or applications.

Of course, there are other ways to pay for mobile transactions – via the wireless carriers for digital goods such as ringtones and music or for nonprofits seeking donations through text as in the Haiti and Chile disaster relief efforts.

However, it seems clear that carriers haven’t yet figured if they want to turn credit card and support all transactions on the monthly mobile phone bill – the easiest mobile commerce option indeed.

Shop talk
For now, the Amazon model works best with ecommerce and mobile commerce. Amazon is now offering for a fee its one-click service to other retailers whose customer base may overlap with Amazon’s.

In addition, Amazon also has shipping data, which is another bugbear for mobile consumers who can’t remember shipping addresses if they are gifting to others.

Now to that all-important question: What happens if the line drops while the consumer is transacting and shopping on the mobile site or application?

Retailers should develop software that asks shoppers to enter their email address and password and then saves every action as the consumer clicks from one page to next. That way, when the consumer returns to that site, she enters her email address and password and is recognized and served the page last visited.

It’s not going to be perfect to shop on mobile simply because of screen size and network availability. But consumers will evolve their mobile shopping habits with regular use and with the spread of WiFi networks, the occurrence of dropped lines will decrease.

Smartphones will spawn smarter shopping – but only on smarter sites and applications. Hit a home run with a user-friendly checkout process.