When the module is powered on, it will automatically start up and automatically search for the network.One signal indicator onboard (slow flash with signal, fast flash without signal)Small size and volume, there is absolutely no GSM module smaller than this moduleFull machine chip processing, reflow soldering, stable performance factory direct salesPower supply can be directly powered by lithium batteryModule model: SIM800L (new module, performance exceeds SIM900/M590)Working voltage: 3.7~4.2V (peak current 1A, please take care of it)Support Network: Global Quad Band NetworkModule size: 2.5cm x 2.3cmThe serial port is a TTL serial port, which can be directly linked with the microcontroller.colour: redMaterial: PCBPackage Contents:1 x Adapter boardOnly the above package content, other products are not included.Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.