All postpaid and prepaid customers can activate the free service of blocking the outgoing call identification, by contacting the Contact Center at 063/9000, or visiting one of Yettel sales locations and requesting this directly.

When activating the service the subscriber chooses one of the three possible service modes:

• Permanent identification blocking. The number identification will be hidden for all calls made by the subscriber from his/her mobile handset.
• Temporary identification blocking. The user should contact the Call Center and request activation of this service. The identification will remain for all calls, but if the subscriber wishes to block his/her ID for certain calls the prefix #31# should be added ahead of the number (e.g. #31#063123456). This will block the identification of that telephone number.
• Permanent identification blocking, with the option of including identification for certain outgoing calls. When the subscriber wants to dial a number with his/her telephone number being visible, the prefix #31# should be added to the telephone number that is dialed.

This service is free of charge for all customers.