Cisco Systems raised its offer for Tandberg on Monday in an effort to overcome complaints from the Norwegian teleconferencing company’s shareholders that its initial offer was not enough.

Cisco, the leading maker of networking equipment, increased its offer to NKr170 a share, or about $3.4bn, from the previous level of NKr153.5, or $3bn. Cisco said it would extend the offer period to December 1 and that the revised deal was its “final price”.