Ad networks have been vital to the growth of Internet advertising and now with the growth of the mobile channel, mobile ad networks are expected to evolve as well.

A major trend expected for mobile ad networks in 2008 will be the evolution of business models and the creation of new success metrics that fit mobile, according to Barry Chu, general manager of advertising for Medio Systems Inc., Seattle.

"This is key to building an ecosystem that produces positive results for advertisers and also increase adoption of mobile advertising as one of the staples of the marketing mix," Mr. Chu said.

Marketers this year will start to understand that simply adapting online campaigns for mobile won't cut the mustard. Mobile requires a different mindset.

"They should think about driving actions that are intuitive to someone who is on-the-go," Mr. Chu said.

He said that driving click-to-call or asking for just a phone entry, rather than filling out a long form, is an example of that.

The new mobile marketplace has spawned companies such as Medio, a provider of mobile search and mobile advertising services for wireless carriers and mobile publishers such as Verizon Wireless, T-Mobile, Canada's Telus Mobility and CBS Sports Mobile.

MedioNow is the company's mobile ad network that integrates ads into mobile searches.

"Specific to mobile search ad networks, we believe 2008 will bring increased participation from the operator community to implement mobile search advertising where possible to provide more volume to networks like us and, in turn, to advertisers," Mr. Chu said.

"[By] the same token, mobile strategies are atop of many publishers' mind, and as they mobilize their content and provide a search solution as a means of enabling their users to find this content, we see that as a huge opportunity for growth and volume for our network, which means more scale for advertiser campaigns on- and off-deck," he said.

Taking this into consideration, it's important that marketers distinguish and understand the different types of mobile advertising and test to see which model works best for their objectives.

So, banner advertising may work for one type of campaign, while mobile search advertising or non-search mobile advertising may do the magic for other campaigns.

Mr. Chu said that brand advertisers may be more inclined to buy banner ads. Direct marketers may buy mobile search advertising, where they pay only when they drive an action from their audience.

"Mobile data consumption is growing fast and marketers need to embrace mobile as the new medium in 2008 to reach their audience 24/7," Mr. Chu said.

"While volume may be low at first compared to online campaign volumes," he said, "this is a good time to perform test campaigns to better understand mobile and what drives response and success for their business."