Vodafone created a radio advert which promoted a phone package that included "unlimited" phone calls, as described in the ad by a male voice.
At the end of the advert a woman read out some limitations to the offer, including that the free calls were only to landlines or other Vodafone mobiles and that the calls were only free for an hour at a time.
A listener complained that the qualifications were difficult to hear because they were read quickly. The ASA upheld that complaint.
"The ASA considered the terms and conditions, which included that the offer applied to calls to landlines and Vodafone mobile numbers only and that a fair use policy and 60-minute call cap applied, were significant clarifications of the 'unlimited' offer and needed to be clear to listeners," said the ASA ruling.
Vodafone claimed that the material was read clearly, saying that the woman's voice had not been speeded up in post production.
According to the ASA ruling, Vodafone "did not believe [the words] were spoken any more quickly than those in other ads that needed to convey a number of points, such as those relating to Financial Services Authority (FSA) products; the qualifications clarified the central offer and did not contradict it and that the CAP [Committee of Advertising Practic] (Broadcast) Radio Advertising Standards Code made no specific mention of the speed at which qualifications should be spoken".
The ASA said, though, that the CAP rules meant that qualifying material should not be read out too quickly.
"The CAP (Broadcast) Radio code specifically stated that ads 'must clarify any important limitations or qualifications, without which a misleading impression of a product or service might be given'," it said.
"We concluded that, because they were delivered too quickly, the important terms and conditions were not clearly audible and the ad could mislead listeners," said the ruling.
The ASA told Vodafone not to re-broadcast the advert.
