One aspect of the present invention relates to user equipment supporting an IMS function, comprising: an application layer configured to provide a user interface for a user to set ON or OFF the IMS function; a SIP layer configured to enable or disable transmission of a SIP signal to a resident network corresponding to user's setting ON or OFF the IMS function in the user interface; and a modem layer configured to change an IMS related Capability of the user equipment related to the IMS function corresponding to user's setting ON or OFF the IMS function in the user interface and communicate with the resident network based on the changed Capability.