1. or remove users via SMS commands. Relay or open time is programmable.2. Can be operated anywhere, no distance restrictions. -band, can be used in the global GSM network.3. No need for remotes or buttons for different users. Safe - use caller ID for identification, unknown callers will be ignored.4. Up to 200 authorized phone numbers can be configured at a given time. One output with a relay rating of 3A or 240VAC for connecting a door or machine switch.5. Multiple applications. (doors, bollards, barriers, garage doors, shutters and access doors or machines). The relay action will return an SMS confirmation to the or authorized phone, this feature can be by the . No call charges. The GSM GPRS trunk exchange rejects calls from authorized numbers and then performs an open or operation on the first "ring".GSM frequency: -band 850 or 900 or 1800 or 1900MHzNetwork: 2GOutput: NC or NO dry contact, 3A or 250VACDC power supply: 9-24VDC or 2APower consumption: 12V input maximum 50mA or average 25mA: Support 3V Antenna: 50 ohm SMA antenna interfaceTemperature range: -20-60Humidity range: 90 percent relative humidityDimensions: 96.5 x 50 x 31.5mm or 3.8 x 1.97 x 1.24inchcolor:BlackMaterial:ABSPackage Contents:1 x GSM door openerOnly the above package content, other products are not included.Note: Light and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is 1-3cm.