General terms to understand: RIO – Relevé d’identité opérateur: French portability authorisation code that allows you to keep your number when you change mobile operators MSISDN: is a unique mobile number attached to each SIM card. Donor: operator hosting the MSISDN at the beginning of a portability process. Recipient: operator initiating the portability request to host a MSISDN from another operator. See our other articles for more information on portability for the UK market or the Belgium market. Follow our step-by-step guide to SIM card activation on our Developer's Portal.