By Gowri Shankar

If you believe everything you read, Apple invented both the mobile Web and the ads that run on it.

If you believe what you see, you know that both were around back when the hottest phone on the market was a Motorola RAZR and the idea of an iPhone was science fiction to the average person.

Today, we live in a world where everyone ? and I mean everyone ? is flocking toward applications and display advertising rules the mobile Web.

Missing from this raucous conversation is SMS ? but it is only SMS that can deliver critical mass and engage consumers across all mobile channels.

The numbers speak for themselves: the reach of SMS is exponentially larger than that of the mobile Web and mobile applications combined, and its effectiveness is unparalleled on any medium.

Virtually every phone on the market has the ability to text and, according to comScore, 150 million Americans use text messaging.

In contrast, there are only about 13 million iPhone and Android users, combined. Yet we still think applications are the answer.

The truth is that applications are part of the answer. In our experience, however, we have found that SMS is a powerful foundational piece to any mobile advertising campaign, on any mobile media channel. 

SMS is door opener
Text messages continue to command our attention. Research from MobileSquared found that 95 percent of people read a text within 15 minutes of receiving it and that 98 percent of all text messages are read.
Neither an application nor banner ad can command that kind of immediate attention. But a text message can invite the recipient to a WAP site, to download an application or to place a call.

SMS builds brand engagement
An absolute requirement of an effective SMS advertising campaign is continuous engagement over time.

Over the course of several years working with brands and publishers, it has been our experience that there is a science to the cadence with which a brand communicates with consumers.

Wait too long between communication, and the end user will have forgotten they opted in and consider the message spam. Over-zealous contact will have the same effect.

Generally, we recommend that a message be sent every seven to 10 days.

For example, Best Buy sends consumers a weekly Deal of the Week message, and less than 1 percent opted out. But there are exceptions ? we worked with CNBC on a campaign that ran during the stock market crash last month, during which 32 messages were sent over the course of two hours, with an identical opt-out rate.

Context is key
Without text, you cannot have context.

In the right context, an advertiser can, in the case of the CNBC example, interact with consumers every four minutes.

The instantaneous nature of SMS affords the luxury of changing creative immediately as a context changes, be it related to medal counts during the 2010 Vancouver Winter Olympics or providing a sponsored link to view the last seconds of the NCAA Championship ? all events that that captivate consumers in the moment, and prompt them to consume more mobile content.

This is where SMS is unmatched in its ability to touch and engage consumers, and why it has been a tremendously successful strategy for the publishers and brands.

Mobile has forced a change in the mentality of advertising ? we can no longer think of a campaign as a six-or twelve-month plan, but a conversation that evolves over time, across all mobile channels, through messaging.

Gowri Shankar is president/CEO of SinglePoint, a Seattle-based mobile messaging advertising network. Reach him at .