Abstract: An operator ePDG access system is provided, including a mobile terminal installed with a first SIM card, and a SIM card reading apparatus installed with a second SIM card. The mobile terminal is configured to access the internet via a network accessed by the first SIM card, establish an IPSec channel with an ePDG, obtain information of the second SIM card from the SIM card reading apparatus, perform data exchange with an operator core network, to perform identity verification on the second SIM card through a secret key negotiation process and perform authentication on the second SIM card through a registration process in an IMS domain, and perform a mobile communication service based on an IMS network by using the information of the second SIM card. This methodology allows a broader means of implementing IMS mobile communications.