Swiss consumers are better protected than ever against internet sites which charge exorbitant rates, according to the Federal Communications Office (Ofcom).
But officials are warning that the cost of dealing with junk email could reach SFr4 billion ($3.17 billion) this year.
A ban on companies automatically connecting web users to the internet at premium rates without their knowledge came into force in Switzerland on April 1.
Ofcom said the total number of complaints from members of the public, including those who had received unusually high telephone bills, had fallen from about 350 in February to 150 last month.
Complaints centred on the fact that so-called web diallers – software programmes used to connect to the internet – were being re-routed to premium-rate numbers without the permission of computer users.
According to Ofcom, access to some websites via a premium rate or 090- number can cost as much as SFr300 ($240) for just 20 seconds.
In Switzerland, premium-rate numbers are used to offer services in the fields of business and marketing (0900), games and competitions (0901) and adult entertainment (0906).
At a media conference on Monday, Ofcom director Marc Furrer said the ban on web diallers was paying off.
"Many people were getting hefty bills,” he told swissinfo.
“But after we prohibited the use of web diallers for [premium-rate] numbers, the number of complaints fell dramatically.”
During the first six months of 2004, Ofcom pulled the plug on just over 900 premium-rate numbers. Only 118 were disconnected during the whole of last year.
“We now only have about five or ten per cent of the complaints that we used to have. That is a good result and is what I call consumer protection,” commented Furrer.
But Ofcom admitted that junk email remained a serious challenge.
Officials said that unsolicited electronic messages - sent to large numbers of people to promote products or services - now represented two-thirds of all email traffic.
“We are not over the worst on this one,” said Furrer, adding that international coordination was needed to fight spam mail.
“The big problem is that it is difficult to know where junk electronic mail comes from and who is actually sending it,” he added.
The Swiss parliament is expected to begin debate later this year on legislation to ban junk emails.
swissinfo with agencies
Just over 900 of the 50,000 premium-rate numbers registered in Switzerland were withdrawn by the authorities in the first half of 2004, compared with 118 for the whole of last year.
The number of complaints about unusually high phone bills has fallen dramatically.
Spam email is expected to cost Switzerland up to SFr4 billion this year.