41 By decision, Ficora may revoke the right to use a number or identifier if: 1) the holder of the right to use the number or identifier does not pay the fee for the numbering decision; 2) the use of the number or identifier is against the numbering decision; or 3) the number or identifier is not taken into use within a reasonable time after the numbering decision or its use has been discontinued, or the holder of the right to use the number or identifier does not rectify his conduct within a one-month deadline in spite of being requested to do so. The right to use a number or an identifier may also be revoked for another similar, very weighty reason relating to the clarity and efficiency of numbering or to the interests of the users, if the holder of the right to use the number or identifier has been given a chance to present his/her view on the matter within a one-month deadline. A consultation is not necessary if the operator holding the access rights has discontinued its operations or the holder of the access rights has ceased to exist due to some other reason. Section 102 Obligations concerning telephone number portability A telecommunications operator shall ensure without delay that a subscriber who has entered into an agreement with the telecommunications operator may, if he or she so wishes, retain his or her telephone number when changing the telecommunications operator providing the service. The validity of a fixed-term communications service agreement concerning the telephone number shall not release a telecommunications operator from the number portability obligation. In a fixed telephone network, a subscriber number specific to a telecommunications area may only be ported within the telecommunications area. A telecommunications operator shall not charge a subscriber for the porting of a telephone number to another telecommunications operator. A telecommunications operator may, however, collect from the other telecommunications operator a one-off payment if the technical process of porting the number generates one-off costs. The one-off payment shall not, however, be so high as to deter the use of the service. In individual cases Ficora may decide on a maximum amount of the one-off payment. The telephone number portability obligation referred to in subsection 1 does not apply to the telecommunications operator when the porting takes place between a fixed telephone network and a mobile communications network. A telecommunications operator in a telephone network shall, for its part, ensure that users have access to a public, comprehensive and charge-free information service giving information on ported telephone numbers. Section 103 Technical regulations on telephone number portability Ficora may issue technical regulations on telephone number portability. Regulations issued by Ficora may relate to: 1) telephone numbers that for technical reasons are exempted from the portability obligation; 2) technical implementation of portability; 3) routing calls to a ported number; 4) organisation of an information service on ported telephone numbers;