The BBC has said it has "contingency plans" lined up to make sure the public are not effected by the strike, which will take place over the course of two weekends - 30 and 31 July and 13 and 14 August - the beginning of the Athens Olympics. In previous strikes this has meant BBC managers manning key positions.
A BBC source said it was hoped the Olympics would not be too badly affected as the corporation took a feed from the host broadcaster, but live programming could be replaced with recorded output.
Bectu has called the strike over the sale of BBC Technology to German-owned Siemens. The division provides most of the BBC's IT services and a walk out by its staff could be devastating.
The confirmation of strike action came as the government said the sale of BBC Technology would not begin its scrutiny until September 6, almost a week after the BBC's target date for the sell-off.
Bectu has also been promised that its opposition to the sale, and concerns about its impact on staff, would be given a full hearing by media secretary Tessa Jowell, which could further delay a final decision.
Bectu assistant general secretary Gerry Morrissey said: "We believe that this sell-off will damage the BBC, and we have asked the DCMS to reject it. Obviously, we welcome the delay that is now built in to the timetable, but we intend going ahead with industrial action unless the BBC and Siemens meet our demands on protection of terms and conditions, pensions, and job security".
Meanwhile, Bectu has begun a short-notice ballot on a revised offer on terms and conditions from Siemens. The consultative ballot closes on 29 July, the day before strike action is due to begin.