There are currently issues with some Cumbria County Council phone lines.
The authority has confirmed it is working with its provider to try and resolve the issue.
People trying many of the council's lines - including the Botchergate-based Carlisle reception and libraries across the county - are being told the number is invalid.
It is affecting calls from landlines and mobiles.
A spokesman for the council said: "We are currently experiencing problems with telephone calls to Cumbria County Council landlines from certain network providers. This is affecting all council services.
"We apologise for any inconvenience.
"We are currently working with service providers to resolve the issues and we hope to have the phone network up and running as soon as possible."
He thanked the public for their patience.
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