The present invention relates to the use of a transponder for wireless communication with the mobile phone, replacing the process of inserting the SIM card inside the device.The object of this patent is to provide a system that allows a plurality of communication devices, whether mobile, portable or fixed, with a second device which has as main feature the validation of user identity with the network of telecomunication providers. In this system, the device A comprises a SIM card that is activated when a device B is in a radius of less than 1 meter. The communication between two devices is done via radio frequency. Device B will make a periodic transmission of data within this radius to determine the continued presence of the device A. The device A containing the SIM card has a passive role, i.e., it only responds to requests from the device B, when receiving a transmission from the same.