A hacker broke into a tourist information telephone line and left an abusive message telling callers that staff were all on drugs.
He replaced the recorded message in protest at what he saw as inflated charges for the information service, which costs 50p a minute.
The man called the Brighton and Hove Council line because he was planning to visit this weekend's Essential Music Festival in Stanmer Park and was looking for accommodation.
He was furious when a recorded message told him the line had changed from a local to a premium rate call-handling service.
The caller, known only as Matt, changed the message to: "Hello, this is tourist information.
"We have changed the number because we are very short of money. We need to buy lots of drugs and go to the festival."
Council technicians managed to return the service to normal shortly afterwards.
A council spokeswoman said: "We did have a problem, but it was discovered quickly and put right. Somebody did manage to alter the message.
"We changed to the premium rate number as a high percentage of calls were going unanswered before. There wasn't the staff to answer them."
She added: "It was decided to introduce the premium line number to give information. Most information can be gathered from the recorded messages, otherwise there are still operators."
The Argus tracked the culprit down to his home town of Colchester, Essex.
He said: "It was great fun. I phoned the tourist information number. I pressed a wrong button by mistake and I was asked for a PIN number.
"I typed the most obvious one in and was immediately offered a list of options. I got a friend to put in an alternative message and then I changed the number so the council couldn't do anything.
"I have made a statement which shows the truth behind overcharging on these lines. Councils shouldn't be allowed to get away with this. I hope the people at Brighton and Hove are embarrassed by all this."
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