Police are investigating an outage of the 111 phone system this morning.
A technical fault prevented people from reaching emergency services in the early hours of Sunday.
It affected callers nationwide for about 45 minutes after midnight, when they received an automated message saying the system was overloaded.
Police said in a statement the fault was with the police system, not Spark.
They switched to a back-up system and it took 40 minutes to clear the backlog.
Police apologised and said they did not know the exact number of callers affected.