The concept of accessibility has been developing in recent years and now that most accesses are managed through RFID cards. However, we can see stagnation in the evolution and development of new technologies, and the access remains limited by something physical, particularly mechanical keys and cards.
With GSM RM-100/115, the access control uses secure mobile communications (calls or SMS's) allowing managing access for a predefined period of time. At the end of that period you can renew the access codes to get new users, equally safely, without changing any physical equipment or needing to move to where you installed the access control, since the system can be reprogrammed remotely by the owner.