Wireless Building Intercom Access Door Opener GSM
Open the door not only by keyboard ,but also but give a free call .
This product = intercom access + GSM door opener
Use cellphone open the door ,no need install extension Building intercom in very house .
Save a lot of cost and trouble to intall extension intercom access device .
Save a lot maintenance cost of each extension device .
With two relays,can control two doors .