IT infrastructure services provider Internap has bought Voxel, a provider of cloud and hosting services, to go after Internet companies in early growth stages.

Internap SVP of product management Paul Carmody said Voxel’s offerings give Internap a means to provide infrastructure services to startups that only use public cloud and to companies in the next stage of growth whose infrastructure requirements merit a combination of cloud and dedicated hosting.

Prior to the US$30m acquisition (closed at the end of 2011), Internap was focused on serving customers with bigger infrastructure needs who require services like customized managed hosting or colocation, Carmody said.

Internap defines the Internet-firm space as the “CTO market” in contrast with the enterprise space it calls the “CIO market”.

“Voxel does a really good job of picking up the CTO market from early inception,” Carmody said. The company has a public-cloud offering for startups and can integrate their cloud infrastructure with dedicated hosting as their requirements grow.

The acquisition does not add any data center space to Internap’s colocation portfolio, as Voxel’s space requirements have been minimal and the company has so far gotten away with leasing colo space in New York, Silicon Valley, Amsterdam and Singapore.

Carmody expects this dynamic to change in the future. Voxel is estimated to have grown 25% in 2011 and is expected to do it again. “We expect that growth trajectory to continue,” Carmody said, adding that Internap was well equipped to provide space and power to support that growth trajectory.

Internap had nine company-controlled data centers as of the end of third quarter and had footprint in 28 facilities controlled by other companies.

The company reports a total of more than 200,000 sq ft of net sellable data center space across all 37 data centers. More than 70% of this space was occupied at the end of third quarter.

In addition to the $30m it paid for Voxel upfront, Internap has agreed to tack on another $5m in cash if the combined company reaches a number of “specific objectives” over the next two years.