By Nisheeth Mohan

Viral marketing began when people started using email to share content with their friends. In the mobile world, viral marketing rides on SMS. The implications of depending on texting when exploiting viral marketing in the mobile arena are significant.

Texting has clearly crossed the line from nice-to-have to must-have functionality. Ross Rubin, director of industry analysis for market researcher NPD Group, said that a recent study had shown that, beyond voice telephony, text messaging is the second-most requested option after a camera phone.

Uses of texting by mobile consumers are very similar to email uses by laptop and desktop users: mass communication, forwarding content and sharing pictures.

As both mobile users and marketers use content sharing, the need to provide the same ease of viral communication has grown.

Instead of simply taking a photo and physically showing it to friends, a mobile device user now wants to take a photo while traveling, immediately upload it to Facebook, and then share the link with his friends across a broader geography.

Or, a user may be reading an online article from The New York Times that she likes and wants to send to a friend.

From the user's standpoint, the entire process -- identify material, share it and have a friend receive it -- feels like a single transaction. Failure of the mobile infrastructure at any point will reflect back on the content provider involved, as well as the wireless carrier.

This is a strong incentive for content providers to provide their own linking capabilities and to give themselves more control over the process.

The increasing rate of content-sharing is putting a strain on the SMS backbone, which, history has proven, lacks the robustness of the Internet.

Content companies employing content-sharing are facing challenges that are new to them -- how to deal with SMS delays and delivery failures, networks and handoffs.

Dependence on SMS has risks, yet not participating in the growing use of viral communications over mobile is not an option as content providers vie for position.

The answer is to deploy SMS-based strategies, rigorously test applications before they are released, and constantly monitor performance from the end-user perspective to spot problems as they occur.

It is important to be able to track a transaction from the time the user or content provider requests a link be sent through validation that the text message was received and that the proper content was downloaded and correctly displayed on the receiver's wireless device.

As transactions grow in complexity, the need for test and monitoring tools that are capable of providing feedback for the entire process also increases.

Success in viral communications is all about taking advantage of SMS capabilities while knowing its limitations and taking safeguards to ensure optimal performance.

Nisheeth Mohan is product manager for mobile solutions and technology at Keynote Systems Inc., San Mateo, CA. Reach him at .