AdMob, which boasts it’s the world’s leading mobile advertising company, has teamed up with MADS, a European mobile ad company, in a strategic alliance to create a global behemoth.

The move is significant because it extends AdMob’s reach in an area where it was relatively weak: Serving ads for high-end publishers across a multitude of mobile channels such as SMS, MMS and the mobile web.

In some ways, you can compare AdMob’s mobile offering to what Google has on the Web: A very open marketplace where advertisers and publishers can sign up easily and immediately — very much like Google’s Adsense, but for mobile.

MADS’s technology, meanwhile, is closed. It is more comparable to DoubleClick’s ad serving technology on the Web. MADS’s mobile ad server technology can customize campaigns for large publishers such as Italy’s Corriere della Sera. It gives carriers and publishers more control over their ad’s look and feel, and can run on a carrier’s deck. So while Google gobbled up DoubleClick two years ago in order to offer both services on the Web, AdMob’s alliance with MADS gives it a way to offer both to its customers in mobile.

AdMob says it serves over 4.6 billion ads per month on applications and content running on mobile web browsers, more than any other network. However, its strength is in the U.S. MADS, by contrast, processes more than 300 million monthly, mostly in Europe. It says it reaches 60 million European consumers a month. MADS has 150 operators and publishers as customers in 15 countries (more info about MADS here).

One of MADS’ competitors is U.S.-based Amobee. Notably, large global carrier Vodafone participated in a $22 million third round of investment in Amobee last August but has since launched partnership agreements with MADS in several Vodafone markets, including The Netherlands, Greece, New Zealand, Romania and Hungary. Might it suggest Vodafone is planning to launch its own mobile ad network, similar to Nokia and Sprint?

MADS was founded in 2006 by Ashu Mathura, who previously sold two companies, including Overloaded, a developer of video games for mobile phones. Overloaded was sold to Norway’s MobileMedia three years ago.