People are being warned that the 999 emergency phone line is down in the south east area of Cambridgeshire, as well as in some areas of neighbouring counties.
The areas affected in Cambridgeshire cover the East Cambridgeshire and Cambridge City districts but telephone lines in the south of Cambridgeshire are now back up and running.
There is also a partial issue with 101 which is currently operating with a reduced service.
Cambridgeshire police were notified of the issues by British Telecom (BT) at about 11am this morning (Tuesday).
Those needing urgent assistance from any of the emergency services, police, fire and ambulance, are advised to call 101 and keep trying if they fail to get through.
It is advised that those calling should consider whether the matter is definitely an emergency while the issues are resolved.
BT are working on resolving the issue which is expected to last for another couple of hours.