What are the 2g SMS collection devices?

There are SMS cats and GSM modems. SMS Cat is a small communication device using GSM and CDMA technology. It receives and sends short messages in real time through 2G network, and is often used in smart homes, factory automatic alarm systems and so on. GSM modem is a special short message device, which sends and receives short messages through GSM, and is widely used in professional application scenarios such as ship maritime information transmission, mobile positioning and tracking. 2G short message collection equipment refers to the short message collection equipment which is based on 2G network technology and sends and receives short messages through 2G/3G network. It is often used in smart homes, factory automatic alarm systems and other scenes.