Hi all - new here and first post. Great resource and community!
I am messing around with a GSM900 module to set up some remote monitoring and control.
I have the GSM900 connected to an UNO R3 and able to send and receive AT/OK commands via the serial monitor (19200/8N1). So I know the GSM900 is alive and functioning.
I am now trying to get connection to the AT&T network here in the US.
I have tested the AT&T SIM in a working handset and can send/receive texts and make/receive calls.
I have the SIM placed into the sim holder of SIM900 and correctly oriented.
I power up the GSM900 and the Power LED and Status LED are hard on. The NetLight is blinking approx every 1s (assume this is the 800ms as per the spec). It never changes to the 3s blinking to indicate cell service and online.
Does anyone have any experience trouble shooting AT&T SIMs and the GSM900 module? I have checked the frequencies supported and all are correct for the USA.
Any other experience, input, suggestions greatly appreciated.
Many thanks,
Matt