The GSM Hat powered by Ibeyonde IoT software is a SMS power-house. The software manages the audience (number + metadata) and lets you schedule transactional as well as bulk SMSes. This is very cost effective if you need to send SMSes on a regular basis. You can use cheap 2G/3G SIM card like the one available form BSNL.
One can respond to SMSes received in real-time. All the responses including missed calls are captured and made available in dashboard. Very handy for companies trying to be in touch with customers via SMS !
This hardware takes in a SIM card and connects to the cellular network. GSM kit has an onboard UPS, which provides several hours of power backup. BSM 24 (physical pin 18) indicates whether the USB power supply is connected. It is up when the USB power is ON. This pin can be used to program saving cached data to the server in case of power failure. Also, there are BSM 26 (physical pin 37) and Blue LED at BSM 22 (physical pin 15). The pin is used to reset the hardware to factory settings. The Blue LED indicates whether Pi is connected to local wifi or is in hotspot mode.
The GSM+USP Hat lets you use your sim card in multiple ways. You can use it to create a PPPoE connection and configure Pi Zero as a WiFi bridge. This setup will give instant internet access over WiFi hotspot to you and your colleagues.
You can also use the serial port hooked to SIM 800C to issue AT commands. The AT commands are useful in sending and receiving SMSes. You can write logic to respond to SMSes automatically.
The SIM800C GSM Hat comes with pre-loaded software that manages your audience's phone number and create SMS sending jobs. The SIM hosting hardware will take care of sending SMSes and filing received SMS.
In many experiments a person SIM card provides better reliability than bulk SMS websites. In our experiments we noted that while SMS gateways gave us 70% delivery rate. A BSNL SIM card gave us 100% delivery rate !
Screenshots displaying workflow of uploading audience and creating bulk SMS jobs. With a typical BSNL sim you can send upto 100 SMSes per day, 1000 SMSes at the rate of rupees 52, costing you less than 6 paisa per SMS. This also gives you the additional capability to respond to received SMSes.
Sceenshots for headless setup dashboard for GSM module.