Children are being warned not to make phoney 999 calls after research found more than half of those made last year were not necessary.
Of the 30m 999 calls handled by BT, 52% were hoax, misdialled or not appropriate for the emergency services.
London Fire Brigade received the most hoax calls, with 10,700, while Greater Manchester Fire Service received 5,700.
Other brigades badly hit included Strathclyde (4,400) West Midlands (4,600) and South Yorkshire (2,700).
BT workers will visit schools across the UK this week showing a video showing the dangers of malicious false calls.
Hoax calls 'cost lives'
Sir Graham Meldrum, chief inspector of fire services, said: "Children think these calls are harmless fun, but calling out the fire brigade to false alarms is not only dangerous but is also a massive drain on finances.
"The 67,000 malicious calls made to fire and rescue services cost an estimated £24m."
Adrian Hosford, director of BT social policy, said: "Hoax calls can cost lives as they tie up vital resources and hinder response times to real emergencies.
"We need to educate young people on the real life consequences that these calls have and also remind them that they are actually breaking the law."
He said hoax calling carried a maximum penalty of up to three months in prison.
The drive is part of BT's Hoax Call Awareness Week and follows earlier campaigns which led to a reduction in the number of malicious calls from phone boxes.