Derbyshire Police has urged members of the public not to "use and abuse" the emergency 999 phone number amid a series of prank calls.
A statement from the force suggests that as many as nine prank calls have been made to the 999 emergency phone number in the last few days.
This means police time and resources is wasted chasing any call made, whether it is serious or not, because each call must be followed up by officers.
A police spokesman said: "As well as our ASB patrols we have attended other incidents which have been reported throughout the night.
"One of which was an abandoned 999 call.
"Over the past couple of days, nine calls have been made from the same mobile number prank calling the 999 system.
"We have to take each 999 call seriously and send officers to each incident. This isn't just wasting the call takers time but also keeping a line busy which somebody may need in a life threatening emergency.
"We also have to send officers to the address where the phone is registered to make sure everything is in order. We urge people to use the 999 system correctly and not waste police time.
"Our non emergency number is 101."