Workers at West Sussex County Council’s contact centres are set to strike on Tuesday, April 2.
Industrial action is expected at the centre - run by Serco - in Durban Road, Bognor Regis.
In a statement, the county council said: “West Sussex County Council’s Contact Centre, run by Serco, is facing disruption due to industrial action involving staff employed by Serco.
“This will affect normal day-to-day operations.
“The centre will be open for its peak hours of 9.00am to 5.30pm instead of 8.00am to 6.00pm.
“It will also be focussing on the priority lines of adults and children’s social care, education, emergency management, the Family Information Service, Highways, Registration, Switchboard, and Blue Badge.
“Other lines may not be available.
“We would ask members of the public to only call if it’s urgent on the day of the strike.
“We hope to be back to normal on Wednesday, but we would ask anyone to delay making any calls until later in the week if possible. Don’t forget, there is a lot of information on the website at www.westsussex.gov.uk.”