System and method for issuing key for door lock at lodging facilities using smart phone

A system for issuing a key for a door lock at lodging facilities, the system comprising:

• a guest smart phone that makes a request for a reservation and payment at lodging facilities, gets an issued key for a door lock when the payment is completed, and performs Bluetooth-communication with the door lock at the lodging facilities using the issued key to open a door;
• a door-lock key issuing server that is requested to make a reservation and payment from the guest smart phone, acts as a proxy to make the reservation and payment at the lodging facilities, issues a key for a door lock with an expiration date corresponding to a predetermined stay, which is valid until the expiration date, to the guest smart phone when the reservation and payment are approved, and provides a password of the key for the door lock to the lodging facilities in real time;
• and
• a lodging-facilities server that approves the reservation and payment made by the door-lock key issuing server, receives the password of the key for the door lock from the door-lock key issuing server, approves the smart phone when accessed by the smart phone, and permits the door to be open by the Bluetooth communication with the approved smart phone.