Videoconferencing app maker Fuzebox raises $20 mln

* Index Ventures' new 350 mln euro tech fund led round

* also Khosla Ventures, Insight Ventures invest

* Index' Mike Volpi to join Fuzebox board

July 12 (Reuters) - FuzeBox, maker of videoconferencing app Fuze, said on Thursday it has raised $20 million from venture firms to expand its sales, marketing and engineering teams.

Fuzebox competes against larger rivals Cisco, Polycom and Logitech in the corporate video conferencing market. It offers visual collaboration service at a fraction of the cost of traditional equipment providers.

Fuzebox has around 2.5 million users, which are holding 78,000 online meetings a day.

The firm was founded as CallWave in 1998. It was a public company from 2004 to 2009 when founders took it private and renamed it FuzeBox.

Index Ventures led the round, making one of the first investments from its new 350 million euro ($431 million) early stage technology fund, with Index partner Mike Volpi also joining the board of Fuzebox.

Index is perhaps best known for backing Skype, now owned by Microsoft Corp, at its early stages. Other investments include mobile-payments company Boku, online-music service Lastfm, and online-storage company Dropbox.

Also Khosla Ventures and Insight Ventures invested in Fuzebox.