BBC journalists are set to strike after voting to reject the corporation's latest proposals in overhauling the pension scheme.
Members of the National Union Of Journalists (NUJ) are to stage two 48-hour strikes starting from next week, with more dates to be announced.
The move follows a 70% majority rejection of the BBC's "final" offer on pensions.
However, the broadcast union Bectu, has voted to accept the BBC's offer.
Union members - who include technicians and production staff - have accepted the offer is "the best that can be achieved through negotiation".
The dispute began over the BBC's plans to reduce a £1.5bn pensions deficit by capping increases in pensionable pay at 1% from next April.
Under the BBC's new offer, the amount employees would have to pay into the pension scheme has been reduced from 7% to 6%.
In return, they would get a career-average benefit pension - based on the average salary over an employee's entire career - that would be revalued by up to 4% each year. The previous offer was 2.5%.
When employees draw their pension, payments will increase automatically each year in line with inflation, by up to 4% - again up from a previous offer of 2.5%.
The NUJ said its members will walk out on 5 and 6 November and again on 15 and 16 November.
General Secretary Jeremy Dear said: "This massive vote against the BBC's latest proposal comes as no surprise, given the fundamental pay more, work longer, get less nature of the offer.
"NUJ members across the BBC have consistently dubbed the proposals a 'pensions robbery'. That hasn't changed. The BBC have now left members with no choice but to take action to defend their pensions."
The NUJ's 4,000 members at the BBC will also refuse to take on additional duties or volunteer for acting-up duties as part of an indefinite work to rule.
Bectu said their position could be reviewed if the pension deficit turns out to be less than £1.5bn.
In an email to staff, the BBC said it was "pleased" Bectu members had accepted the offer.
It added: "We urge the NUJ to reconsider its position in relation to the joint union result."