TEC800 GSM PHONE REMOTE CONTROL SYSTEM In cases where up to 4 doors are required to be opened, our tec800 4-relay GSM remote door control device can be easily used. It can be easily used in products such as arm barriers, sliding door motors, automatic shutters and garage doors. It has a 3060 memory replaceable memory module. It is very easy to manage. Feedback is given via SMS. It is a cheap, durable and practical domestic production device. A sim card must be inserted into it.