The invention relates to a method for communicating data between a communication system and a mobile radio-communication network through an Internet Protocol data communication channel. The communication system comprises a host device and a portable object cooperating with the host device. According to the invention, the portable object determines in which geographical place the communication system is located. The portable object determines whether at least one subscription before a mobile radio-communication network operator over a data communication channel using the IP within the geographical place exists or not. And, if at least one subscription before a mobile radio network operator exists, then the portable object sends to the host device a request for reading configuration data relating to an access to the data communication channel using the IP. The invention relates also to corresponding portable object and communication system comprising a host device and the portable object cooperating with the host device.