BT are working to sort problems which are affecting phones in parts of Fife, Perthshire, and Aberdeenshire.
People have been asked not to make any non-urgent calls while engineers tackle the problem – this will leave lines free for any emergencies.
Fife Police posted the update on their Facebook page to highlight how 999 calls CAN still be made if your phone service is down.
It said BT was working to restore full service.
The statement added: “We are asking people not to make any non-urgent calls for the time being so that all the available phone lines can be used for real emergencies.
Even then, some people may be unable to use their own phones, or public payphones, to call the 999 emergency services.
“You might be able to call your nearest police station directly or 101 even if the 999 service has been affected.
“You can also try dialling 999 from a mobile phone, if you have access to one, since the mobile phone networks may still be working normally. If your mobile network is not operational, you may still be able to make an emergency call via another mobile network by calling 999 or 112.
“You could also seek help by going to your nearest police station, hospital, fire or ambulance station in person.’’