Hertfordshire Constabulary’s control room was hit by communications disruption after an attempted metal theft last night.
Phone lines and internet access at the centre, in Welwyn Garden City, became affected at around 8pm and officers had to switch to a back-up systems.
The force said it did not believe any 999 calls had been lost and that the service was now running as normal, although online reporting maybe delayed.
Assistant Chief Constable Alison Roome-Gifford is leading the contingency group to ensure service is not affected.
She said: “Our priorities as always are to ensure members of the public, particularly those who are vulnerable, are safe and to enable our staff to work effectively and safely.
"Back-up systems quickly became effective and we don’t believe any 999 calls were lost. I would also like to reassure the public that operationally there have been no adverse effects and policing service levels have been maintained.
“This matter is currently being dealt with as a matter of urgency by BT, with whom we are working very closely. We recognise that in this case as well as the impact on the public and the police, they are victims of crime.
"Our 999 and non-emergency 101 numbers are working however, we are still facing some difficulties in sending and receiving external emails and making and receiving phone calls to some regular land-lines. Our IT experts are working tirelessly to rectify these issues as soon as possible.
“We can confirm that the problems have been caused by the attempted theft of cabling and this is being fully investigated by the dedicated Operation Devon (metal theft) team whose role it is to prevent and detect these crimes.”
Police said the area of the attempted theft could not be revealed for security reasons.