Call setup method for mobile virtual private network and access point apparatus thereof

A call setup method, adaptable to a Mobile Virtual Private Network (MVPN), wherein the MVPN comprises a plurality of access point apparatuses, at least one database, and a plurality of users, the database records a private extension number, a user phone number, and a user identity module of each of the users, the database further records a link address and an identity information of each of the access point apparatuses, and the users comprise a Mobile Origination (MO) user and a Mobile Termination (MT) user, the call setup method comprising:

• receiving a call setup request message for setting up a call with the MT user from the MO user by using the access point apparatus corresponding to the MO user;
• searching for the private extension number or the user phone number of the MT user in the database;
• when the private extension number or the user phone number of the MT user is in the database, inquiring each of the access point apparatuses whether the MT user is within a coverage area of any one of the access point apparatuses;
• and
• when the MT user is within the coverage area of one of the access point apparatuses, responding an inquiry result to the MO user through the access point apparatus corresponding to the MT user by using the MT user, and setting up the call through the access point apparatus corresponding to the MO user and the access point apparatus corresponding to the MT user by using the MO user and the MT user;
• and
• when the private extension number and the user phone number of the MT user are in the database and the MT user is within the coverage area of one of the access point apparatuses, receiving the call setup request message from the access point apparatus corresponding to the MO user by using the access point apparatus corresponding to the MT user, and then setting up the call through the access point apparatuses corresponding to the link addresses by using the MO user and the MT user.