No SIM card on the modem G736-AS2 generates error 8 'No Modem'.

FAQ #101621

 

The main reason of the error 8 is that the modem is not connected.
Another possibility is that there is no SIM card inserted into the GSM Modem G736-AS2 with version V3.01.C3 or newer.
It's also possible that there is a card inserted but the card is not valid anymore or hasn't been activated yet. Please pay attention that with Version V3.01.C3 or newer only 1.8 or 3V SIM cards are supported. Unfortunately there is no indication on the SIM card if it's a 1.8/3V or a 5 V card. If you aren't sure, please ask you provider to exchange the SIM card.
There is also the error 'No modem', if there is a very weak signal, the FDS Led on the modem is blinking fast and therefore the modem is unable to register to the GSM network.

This is the list of possible reasons:

No Modem

Error 8

No modem connected to the serial port Modem incorrectly wired No power to the modem No or invalid SIM card inserted No registration to the GSM network due to bad signal quality (FDS LED blinking fast)

Note:
If you are testing the modem with an application like Hyperterminal on a laptop, it isn't possible to get answers from the modem unless you have inserted a valid SIM card.
The modems with version V2.07.B2 or older don't have the same behavior. There is only a 'No modem' error if there's no modem connected, the modem is not correctly wired or the modem is not powered.