Hello,
I hope someone can help me with this, I'm using a Siemens TC35 GSM modem and connecting it via USB to Serial converter to a laptop, it works fine and responds to the AT commands when not loaded with a SIM card, but, as soon as I add the SIM card, the status LED blinks for 5 or 6 times then goes OFF and the modem stops responding to any commands.
thank you
Bad SIM, No Antenna?