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Not registered SIM800C

reza147

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Hello
We had a few SIM800C that worked well last month. They connected to the grid after 5 seconds, and the net_LED flashed for 64 to 3000 seconds. Then we would call or text them and get them.

But a few days ago a problem occurred! These wires do not connect to the network and the net_LED always flashes for 64 to 800!

Since we have 10 of these modules, all of which have been well connected to the network in the past, we are sure that the problem is not the module or the hardware.

We used two types of SIM cards but the problem was not solved.
Our module also has an antenna.

We think maybe this week the telecommunications has been updated and now the SIM800C can not be with that matching. And GSM cannot be registered.

Can you give us an order to solve the problem?
Can anyone give an AT command for matching with the telecommunications?

Interestingly, this problem is less seen in the type of SIM808 and SIM800A!
For simplicity, we used only a SIM card, an antenna and a USB to TTL converter and a laptop.

CC1.png
 

FvM

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I would systematically check the device status by executing the respective commands, SIM card detected, +CPIN?, enabling extended result codes for +CREG, detected networks.
 

reza147

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Hello
As soon as I connect the module to the laptop with converter TTL, the following data appears after the AT command.
"+CPIN: NOT READY"
But I do not know the reason?

Interestingly, this module only recognizes one SIM card and does not connect to other SIM cards! And this problem has just arisen!

When I test with the SIM800A module, all the SIM cards are connected!
 

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FvM

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There are various reports about SIM card problems with SIM800C. Some are stating RF interferences (antenna too near to SIM card respectively module, bad antenna matching). I know that such problems can happen with GSM modules, it's at least worth a try. If problem occurs, the card would be initially detected and deactivated when the modules tries to connect to the network. Can be differentiated from the case that the SIM card isn't initially detected.
 

reza147

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Hello
How can we see the date of SIM800C production?
So we can compare our purchases.

I see the GSM Revision with the "At+GMR" command, but I am looking for a better document.
 

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