Digital media measurer ComScore has purchased M:Metrics for $44.3 million, adding the Seattle-based mobile trend tracking capabilities to its extensive online portfolio. As mobile begins to shift from a completely voice-centric platform to one encompassing multimedia, Web browsing and other content consumption, the traditional media tracking agencies are starting to take notice, forming their own mobile divisions and buying up companies like M:Metrics and Telephia.

ComScore focuses solely on digital media, tracking customer habits and transactions on the PC and wireline Internet, just as M:Metrics tracks them on the handset screen. ComScore monitors 2 million consumers’ browsing and transaction patterns through PC clients that capture their every move online. M:Metrics own data monitoring solution functions similarly, using a smartphone-based client to track the browsing and purchasing habits of 4000 consumers in the US and UK. M:Metrics supplements that hard data with a monthly survey going to 40,000 mobile device users and an ad-tracking service that follows click-through and impression rates for mobile advertising across a wide variety of sites.

M:Metrics has about 180 clients compared to ComScore’s 950, but ComScore said there is opportunity to cross-sell its new mobile products to its existing customer base as well as bring ComScore’s traditional Web products to the mobile industry. “We see compelling opportunities to increase the market penetration of M:Metrics’ products within ComScore’s customer base of over 950 clients and to cross-sell ComScore’s portfolio of products into the wireless industry, including the major carriers and device manufacturers,” ComScore CEO Magid Abraham said in a statement “In addition, we plan to leverage ComScore’s panel, technology infrastructure and sales force to expand the metered mobile panel and develop new offerings that can significantly increase the growth and profitability of M:Metrics’ business.”

Last Year, The Nielsen Co. launched its own mobile media tracking service and then bought telecom metrics company Telephia for an undisclosed amount. Unlike ComScore, Nielsen tracks the entire gamut of the media industry from movies to TV to the Internet.