Simcom SIM800H no network, AT ok

I’m working on the sim800l module.
It worked for a few days and after that, it is not connecting to the network.
I checked the power supply and Tx Rx connection which are correct. I’m using a 3.8v Lippo battery for power needs.
AT commands are working but no network, not connecting to the network (nw led blinking every 1s 7times and then 4-5s delay )

what could be the possible solution?

Hello and welcome!

How are you powering the module and charging the battery?

Do you have a proper level shifter or does your module handle this for you?

What errors are you receiving on the Serial port? Does the SIM have access to the network on a phone for example? If you try to connect in a different area (as to use a different provider antenna) are you still unable to connect?

Thanx for reply

I directly connected lippo battery to module which is 3.8v
And I’m charging this battery separately with mobile phone.(by disconnecting it from module)

I also designed level shifter using voltage divider rule for Rx Tx pin of module.

Sim card is working in phone and also in other gsm module( A6 GSM module).

Some of the at commands working (commands that don’t require network connection like at, ats0, at+csq so on )

If I try to run atd+mobno
It say error no carrier

Alternatively, you can check a simple “proper” lever shifter suggested by the manufacturer on this document on page 32, for either 3.3v or 5v logic on your microcontroller.

What interface are you trying to use? TCP, UDP, HTTP?
If what you are trying to do can be resolved with simple HTTP requests, I recommend you to use the HTTP interface (you can check examples on this document starting at page 8). It’s usually the simplest and more stable way to communicate with a server on this chip.

I’m sorry but I think you don’t understand the issue

Module is not registering on network
Network led is blinking for 7 times (1 s delay ) and then 3-4 sec delay that means module is searching for network to register on.

So first step is to get module connected to network. And then all this thing http, udo to whatever you said.

So question is why it is not registering on network even if power supply is proper and sim card is also working.

You have different ways to connect to the network depending on the method you are using, some easier than other. Since you’ve said that it did work for some time, it means that you’ve successfully use one of those at least once. That’s a completely different scenario as just “it is not registering on the network”.

So my answer to your question is another question: which method where you using when it did work?