This GSM door opener with a remote on/off switch for authorized calls for free calls, which can be operated from anywhere without distance restrictions.Features:1. 850/900/1800/1900MHz quad band, can be used in the global GSM network.2. No call charges. The GSM relay switch answers the call from the authorized number and then performs an on/off operation on the first "ringing".3. Security - Use the caller ID to identify and ignore unknown callers.4. Add or remove users with the SMS Text command.5. There is no need to provide remote controls or buttons for different users.6. Up to 200 authorized phone numbers can be configured at the specified time.7. The relay operation will return a text message confirmation to the owner or authorized call, which can be edited by the user.8. The relay closing or opening time is programmable.9. With metal casing, IP30 protection level. The metal casing and system are safely isolated, especially suitable for industrial control applications.10. Small size and support for wall mounting.11. Multiple applications.Specification:Model: RTU5024GSM frequency: 850/900/1800 / 1900MHzNetwork type: 2GSupport: 2G, 3G, 4GDigital output: NC / NO dry contact, 3A / 240VACDC power supply: 9-24VDC / 2ASIM card: standard SIM cardAntenna: 50Ω SMA antenna interfaceTemperature range: -20~ + 60°CHumidity range: relative humidity 90%Package Size: about 13 x 9.5 x 3cm/5.12 x 3.74 x 1.18inPackage List:1 x GSM Mobile Phone Access Controller1 x Antenna2 x Terminal1 x English Manual.Note:Please note that the new type and old type of this product will be sent randomly, and make sure you will not mind before ordering.