What do you call a GSM 1400? Is this an Arduino MKR GSM 1400?? (If so what is the code running on that MKR GSM 1400?)Your loop makes no sense either, you try to read data from software serial not know!no if there is something there (will get you -1)
the Arduino MKR GSM 1400 is a full Arduino, it's not a side modem you drive through Serial with AT commands. You can program its Atmel SAMD21 processor directly and leverage through the libraires the SARAU201 GSM moduleyou probably don't need the UNO at all.
I was trying to link a project that I have completed on the UNO with GSM capability. I will look into converting the UNO code into the MKR GSM1400 instead. It seems this might be the easier approach.