West Suffolk Hospital in Bury St Edmunds has apologised to patients after phone line issues meant it could not receive calls.
West Suffolk NHS Foundation Trust posted on social media to direct patients to a temporary phone number while the issue is resolved.
However, the hospital said it is still able to make outbound calls.
The trust said on Facebook: "Unfortunately, we will not be able to transfer calls to wards or take messages to patients. Please only use this temporary number in a genuine emergency.
"Please be patient with us whilst we resolve this issue. Apologies for any inconvenience."
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