Phone lines are down in locations across Sussex.
Residents have reported no service in areas of Brighton as well as Polegate and Eastbourne.
Calls to numbers in affected areas all result in the engaged tone. One customer has contacted the Argus to say he is frantically trying and failing to get through to the Royal Sussex County Hospital.
A BT spokeswoman said: “We're really sorry but we've got a problem at the moment in sme areas, which means that some of our customers will be having trouble with their telephone line. We're trying to fix the problem as quickly as we can.”