I am looking for someone who has experience with sending and receiving SMS text messages with a GSM 1400. I have a couple of questions to ask about this, please read on....
I have used an Adafruit FONA 800 GSM shield on an Arduino UNO before and now I am currently working with an Adafruit FONA 3G with an ESP32. Both of these FONAs use SimCOM cell modules, the FONA 800 is a 2G unit, and the FONA 3G, as it's name implies, is a 3G module. For my project, I am only using SMS messages to communicate with the micro controller.
So here's my problem, while 'stress testing' my code, I've found it's possible to overwhelm the cell module with SMS messages. Here's what I mean by that....
My code first checks that the cell module is registered on the network, if it is on the network, then it checks for SMS messages. When a SMS is received, the data in the message is processed and a SMS reply is sent back. My code works fine, if I send a SMS message, I get a reply shortly afterwards. Send another SMS and wait, I get a reply.
The problem I am having is when I send 5 quick SMS messages in a row. When this happens, the first SMS will be processed and a reply sent. Then the next time through the loop, the test for the module registered on the network will come back false. The module recovers after 30 seconds or so, and reports it is connected to the cell network, then the remaining, unprocessed, SMS messages will be processed.
I noticed the GSM 1400 uses a uBlox cell module and basically, I'm wondering if it works any better than the SimCOM modules I've used?
I'm wondering if anyone can tell me how the uBlox module fares when bombarded with SMS messages before I purchase one to test.