The agency said the 12-month brief would cover both traditional and social media and focus on highlighting the benefits of cloud-based unified comms to businesses.
"The programme will include a series of strategic campaigns connecting 8x8 to the mainstream news agenda as well as an integrated press office focused on customer communications, event support and social media engagement," Capella said.
8x8 is part of NASDAQ-listed 8x8 Inc, which services more than 40,000 business customers globally. UK customers include London Overground Rail Operations and Empire Cinemas.
Capella founder Gareth Thomas said: "8x8 has some pretty special technology, but this brief is about showcasing the opportunities its innovative solutions unlock for businesses. We're really excited to be working with 8x8 as the company continues its rapid growth."
Deborah Robertson, UK marketing director of 8x8 Solutions, said: "As the economic recovery gathers pace, we're seeing companies invest in the smartest new cloud technology to give them an edge over competitors. 8x8 wants to capitalise on this by raising our profile in the UK and we're delighted to be working with Capella to help us do this."
Thomas founded Capella in 2012 after leaving his role as director of Brands2Life.