Trai said it had given this direction to telcos after examining several consumer complaints in the matter. In a statement, Trai said all access service providers, including BSNL and MTNL [Get Quote], would ensure that its direction were followed within 45 days.

The authority said that there could be accidental activation of VAS through the method of pressing a key to express consent.

Operators will now have to convey to the customer in writing or through SMS or FAX or e-mail, all the details of a value-added service.

"The accidental activation of such VAS through Out-Bound-Dialer (OBD) call could happen without understanding the implications of such offer," Trai said in its order.

Trai observed that the system of pressing a button to get a VAS activated was not a sound method as children at home could unintentionally press a particular key. There may also be possibilities that a customer may not have listened to the announcements fully or did not understand the offer and pressed a particular key unintentionally, thereby activating the service, it said.

Trai had received a number of complaints from telecom users, alleging activation of caller ring-back tunes through the facility of "press star to copy hello tunes" without explicit consent.

Most of the service providers induce the customers through recorded announcements to go for VAS. "Such examination of the complaints revealed that there is a likelihood of consumers subscribing to VAS accidentally or unintentionally by pressing the '(star) key' in the mobile handset or the telephone set during the call and that this process for obtaining the explicit consent is not in line with the direction of the authority," Trai said.