The invention discloses an extension access method and a wireless user exchange device and relates to the information technical field. The complexity that an extension is accessed into a network can be reduced. The extension access method comprises receiving an SIP (Session Initiation Protocol) calling message initiated by the extension; enabling the SIP calling message to be converted into a No. 7 signaling calling message; sending the No. 7 signaling calling message to a communication network. The extension access method and the wireless user exchange device are suitable for implementation of the mutual dialing between internal extensions and external phones of an enterprise.