Tandberg's board has agreed to the deal, but minority shareholders said last week that Cisco's $3 billion cash offer was too low.

The offer period was set to expire Monday. Cisco extended it until Nov. 18.

Tandberg shares closed Monday at 151.80 Norwegian kroner on the Oslo stock exchange, just below Cisco's offer for 153.50 kroner, indicating that investors don't expect Cisco to sweeten its deal.

Tandberg is the leading global maker of videoconferencing equipment for business users, a growing market that Cisco has also entered.

A service of YellowBrix, Inc.