One of the hot topics at this year's Mobile World Congress was the rise and future evolution of mobile social networking.

Online social-media networks have empowered users all over the world as many consumers have been given the tools to become producers of online content. Mobile social networking promises to extend these opportunities to the many emerging markets in which few people have fixed internet access.

Jordy Mont-Reynaud is lead mobile developer at Bebo, an online media network with 40 million members. In his view, the main challenge for both operators and social-network companies is to achieve what he calls “ambient communication” in the mobile world.

Ambient communication is what happens when online social networks get news feeds and automatic e-mail updates, allowing users to communicate with more people more efficiently.

“Instead of having to look at someone's profile page, you can get automatically alerted when your contacts do something interesting, whether it is posting a photo or a blog update,” he says. “In the mobile world, the possibility of pushing messages out to users really takes this type of ambient communication to the next level, because it gives you that instantaneous aspect.”

The challenge in the world of mobile social networking, Mont-Reynaud says, is that the only way to get this kind of functionality to a true mass market today is via SMS. However, people typically cannot send unlimited numbers of SMS messages for free and social-networking news feeds create constant streams of messages that may set up consumers for an unexpected “bill shock” - hardly something that users in emerging markets will tolerate.

While SMS is too expensive at social-networking volumes, Mont-Reynaud says the alternatives are either handset-specific or not broadly supported.

“Mobile social networking will realize only a fraction of its potential until we figure this out,” he says. “The holy grail is some push mechanism that can deliver wide-scale ambient communication without being too expensive for the user. Without it, you will miss 90 percent of the traffic that you get on the web.

“Fundamentally, it is about the business model of the online world versus the business model of the mobile world.”

However, until Mont-Reynaud's holy grail is found, operators can still earn revenues from social networking because it increases use of other services that they provide.

“As a user, you might respond to a message with a voice call, or maybe there is a link in the update message that you click and then you generate revenue for the operator by using its data service,” he says.