Dynamic method for determining a list of services in an SIP network

A method is provided for determining a list of services for a user of a customer device of operator network implementing SIP. The method includes: the customer device inserts a list of services that it has the technical means to provide into a request for registration with the operator network; where appropriate, each intermediate network relating the customer device to the operator network transmits the request to the operator network after having deleted therefrom or marked, in the list of services, all services that the intermediate network does not have technical means to provide and/or for which the intermediate network does not have a use agreement with the operator of the upstream and/or downstream network to which it is connected; and the operator network obtains a definitive list by extracting services to which the user is entitled among the services that the operator network has the technical means to provide.