The system will be shut down between 10.30pm and 3am with those wishing to call during this period being asked to use the switchboard.
A hospital spokesman said: “There is a potential that if people ring any other number other than the hospital switchboard between 10.30pm and 3am, they may not be able to get through straight away.
“If you need to talk to a member of staff, please contact the hospital switchboard on 01205 364801 who will be able transfer your call to the right ward or department.
“Contingency plans are in place to ensure patients’ safety is maintained. Any routine calls and enquiries should be made before 10.30pm to avoid any problems.”
They apologised for any inconvenience this may cause.