In this case, the network connection may not be successful. Follow the steps below to troubleshoot:
1. Firstly, check the hardware connection:

• Please check if the MAIN antenna is properly connected, the SIM card does not support hot swapping. Please install the SIM card and antenna with the power off, and after registering the network, the NET indicator will blink;
  
• Confirm whether the connected SIM card can make normal calls and surf the Internet on mobile phones and other devices, and try to avoid using IoT cards with many restrictions during the test stage, please give priority to using ordinary mobile phone SIM cards;
• It is recommended to replace the SIM cards of different operators. Under the comparative test, the network frequency bands and base station layout supported by different operators are different. Changing the card can also eliminate problems such as card arrears.
  

2. After confirming that there is no problem with the hardware, use the following command to debug the network:

• Since all cellular modules are shipped only after passing SIM card testing without issues, they are default assigned with an APN. Different operators have different APNs, so please configure the APN for distinction. APNs for some operators are as follows:

 China Mobile:  AT+CGDCONT=1,"IP","CMNET"
 China Unicom:  AT+CGDCONT=1,"IP","3GNET" 	
 China Telecom: AT+CGDCONT=1,"IP","CTNET"	
 AT&T:          AT+CGDCONT=1,"IP","PHONE"
 Vodafone:      AT+CGDCONT=1,"IP","portalnmms

• Sometimes you also need to set the APN username and password:

  AT+CGAUTH=1,1,"<your username>","<your password>"

• Set to automatic network search:

  AT+CNMP=2

• Turn on radio, turn off flight mode:

  AT+CFUN=1  

• Save configuration:

  AT&W0

3. After confirming that the hardware is correct and there is no problem, you can use these commands to check the network status:

Check if the SIM card is in good contact: AT+CPIN?  
Check if the RF is turned on (turn off flight mode): AT+CFUN?  
Check operator access status: AT+COPS?
Check network status: AT+CPSI?
Check if successfully registered to the network: AT+CGREG?
Check the signal quality of the current environment: AT+CSQ
Check if the network mode settings are correct: AT+CNMP?
Check if the APN configuration is done: AT+CGDCONT?
Check firmware version: AT+SIMCOMATI 

Please check the Enter key for line breaks, default 115200 baud rate, AT PORT COM port, send one command at a time. After correctly registering to the network, it will be as shown below:

If not registered to the network, configure the network

• Check if the network mode settings are correct:

  AT+CNMP=2

• Turn off flight mode:

   AT+CFUN=1

If it is a Linux system, you can use a tool such as minicom to view:

To save valuable R&D time, it is recommended to use a phone card that supports making calls during the testing and validation phase, and confirm that there are no hardware issues before using the IoT card that requires troubleshooting. The IoT card has many restrictions, mainly including the following points:

• Account suspended, IoT cards (data cards) that do not support calling and SMS functions will bind the cellular module and the SIM card's IMEI, allowing only one card per device (policy stipulation); if you change the device, you can ask the IoT card operator to check the card status and unlock it, but it is not recommended to frequently change devices for use
• Some private (personally built base stations) IoT cards may not be supported. It is recommended to apply for guaranteed IoT cards at the branches of the major operators
• Confirm if the frequency bands supported by the IoT card cover the frequency bands supported by the module
• If you do not have an APN set, please configure the APN with the following command.

AT+CGDCONT=1,"IP","Your_APN"   

Sometimes, you also need to set the APN username and password:

AT+CGAUTH=1,1,"<your username>","<your password>"

Different dial-up methods result in different IP addresses, each with its own characteristics. Please refer to the table below for details:

• Linux dial-up
  • Raspberry_Pi_networked_via_RNDIS
  • A7600X_RNDIS_Dail-up_Networking
  • SIM7600X_ECM_Dail-up
  • SIM820X_RNDIS_Dial-Up
  • NDIS_Dial-Up
• Windows dial-up:
  • Windows_NDIS_Dail-Up
  • Windows RNDIS_Dial-Up

It is due to the echo not being turned on. The SIM7600X can send the following commands followed by Enter (here, sending ATE1 is also not visible, similar to entering a password; please confirm and type blindly after pressing the key), and after displaying OK, the echo is successfully turned on.

ATE1

• Usually, the CSQ signal value is automatically printed continuously. You can turn it off using the following command; change the parameter to 1,0 to turn it on:

AT+AUTOCSQ=0,0

• Close the ModemManager process to prevent useless data from being displayed when debugging the AT serial port with minicom

sudo su
killall ModemManager

Open the Raspberry Pi terminal and enter the following command to enter the configuration interface

sudo raspi-config

1. Select Interfacing Options -> Serial, disable shell access, and enable the hardware serial port as shown below: <br/
2. 
   

The serial device number for Raspberry Pi 5/2B/ZERO is ttyAMA0; you can confirm this with the following command line, serial0 is the selected serial device number, as shown in the figure:

ls -l /dev/serial*

• If you want to swap the mapping of ttyAMA0 and ttyS0, assign serial0 to ttyAMA0, and select ttyAMA0 serial port, you can modify the system configuration file /boot/config.txt

sudo nano /boot/config.txt

Add in the file:

dtoverlay=pi3-disable-bt

Sometimes you can ping an IP but not a domain name, which is a DNS server issue. Please refer to the following steps to configure the DNS server Check the current DNS

cat /etc/resolv.conf

• Back up the original DNS configuration file first

sudo mv /etc/resolv.conf resolv_bk.conf

• Re-edit a DNS configuration file

sudo nano /etc/resolv.conf

• Add Alibaba Cloud DNS server:

nameserver 223.5.5.5

• Or Google DNS server

nameserver 8.8.8.8

• Go ping the domain name for testing, use the corresponding network card, here usb0

ping qq.com -I usb0 

• Lock the file to prevent tampering, unlock and change to - i

sudo chattr +i /etc/resolv.conf

You can set it using the following commands:

AT+CGDCONT=1,"IPV6","Your_APN" //Switch to IPV6
AT+CGDCONT=1,"IP","Your_APN"        //Switch back to IPV4
Different operators have different APNs, so attention should be paid to setting them correctly. Common APNs are as follows:
China Mobile: cmnet
China Unicom: 3gnet	
China Telecom: ctnet	
Verizon: Wireless vzwinternet	
AT&T: phone	
T-Mobile: fast.t-mobile.com	
Vodafone: portalnmms	
Orange: orange.fr

Sure, the detailed steps for UART dialing are as follows:
SIM7600X PPP Dail-up

• Under normal circumstances, SIM7600X is automatically dialed when connected to the Windows system, so there is no need to redial. Redialing will return NO CARRIER
• If you still can't dial up to access the Internet, please use the following command to change to the Windows default dial-up mode

  AT+CUSBPIDSWITCH=9001,1,1 

• Display as turned off and mobile network not enabled, you can ignore it and go online directly;

• You can also install the driver SIM7600X dial-up Driver to update the network card

• After installing the driver, the network card shows as enabled

• Generally, the default configuration of SIM7600 is to automatically select the network standard, and it is likely to choose 2G Internet access; if you need to force the use of 4G mode, you need to enter the following AT command configuration:
  

AT+CNMP=38    //Fixed 4G LTE, if there is no local 4G coverage, you may not be able to register to the network

 If 4G has been fixed and the speed is still not ideal, it may be a frequency band problem;

AT+CNBP?  //Backup the current band (the returned band information can be copied to Notepad, etc.)

AT+CNBP=0x0002000000400183,0x000001E000000000,0x0000000000000021    //After returning OK, measure the speed

AT+CNBP=0x0002000004400180,0x000001E000000000,0x000000000000003F   //If the speed doesn't improve, try this

• Different operators have different APNs (similar to network addresses), please set the operator's APN

AT+CGDCONT=1,"IP","Your_APN"

• Different operators have varying coverage ranges for their base stations, usually with major mainstream operators having wider coverage areas

It is recommended to use a SIM card from a mainstream operator

• The module may not cooperate with some niche operators, so it does not have its certification. Please use a SIM card from a certified mainstream operator instead, and make sure that the card has sufficient tariffs to make normal calls and surf the Internet.

• After the host dials up using SIM7600X, it obtains a local network IP or an Internal network IP assigned by the operator (with IPv4 public addresses becoming increasingly scarce, more and more users are using Internal networks, and most operators only provide Internet access functionality; public network IPs are categorized as commercial packages that require additional application). Intranet penetration is a viable solution.

• Yes, hosts like the Raspberry Pi can connect to multiple networks simultaneously
• The operating system decides the transmission path of data packets based on the priority of the routing table, so the Internet speed usually cannot be increased by adding multiple network cards

• 1) It is recommended to test with a SIM card from a different operator: different operators support different 5G bands, and changing the card can also eliminate other card issues
• 2) Confirm the 4G signal strength at this location. Weak signals can lead to a decrease in network speed. You can switch to a different network sector or go to other city areas for testing: Different regions are covered by different carrier networks, resulting in different 5G bands in different places.
• 3) Please check if the APN settings are correct. Different operator APN parameters can affect network speed performance:

AT+CGDCONT?

• 4) Please provide sufficient power for the module. Insufficient power supply can lead to network instability. Sufficient power can ensure stable Internet speed
• 5) It could be that the antenna frequency band does not cover the frequency band used by your operator. Please replace with the full-band high-gain antenna suitable for local testing and connect all antennas. All antennas are useful, otherwise they may also cause network issues

Please plug the GPS antenna into the GNSS antenna mount, and place the receiver tag face down in the open outdoor visual sky (note that the test cannot be done in rainy weather), and wait for about 1-5 minutes (the specific time depends on the test environment) to receive the positioning signal;

• If the positioning is slow, it is recommended to use the following command to enable the module to power the antenna and accelerate positioning:

AT+CVAUXS=1

AT+CGPSNMEA=197119

Or use the following command to obtain location information

AT+CGPSINFOCFG=1,31

AT+CGPSAUTO=1 

• After turning on GPS on the AT Port debugging serial port (Linux default ttyUSB2), then open the NMEA port (Linux default ttyUSB1) to obtain dynamic information:

AT+CGPS=1	      //Turn on GPS
AT+CGPSINFO           //Print GPS information to serial port
AT+CGPSAUTO=1         //Enable auto-location on startup
AT+CGPSNMEAPORTCFG=3  //Enable NMEA print GPS information

 For more detailed steps, please refer to the following link:
The longitude and latitude obtained by the SIM7600X module are in units of minutes, whereas the commonly used format is in degrees. For more details, please refer to the section below.

• SIM7600X Positioning via uSTAR
• SIM7600G-H 4G for Jetson Nano Precisely Locates in Gaode Map API
• SIMXXX Locates My Location on Gaode Map

The common commands for the LBS base station positioning function of the SIM7600X are as follows:

AT+CLBS=?  //View the range of parameters that can be set
AT+CNETSTART//Open the network; If the network fails to open, you can use the command AT+CNETSTOP to close it and then open it
AT+CLBS=1 //Get the current latitude and longitude
AT+CLBS=2 //Get the detailed address

Please click the link below:
SIM7600X Common Commands

You can use the following command to enable VOLTE function:

 at+voltesetting=1
 at+cnv=/nv/item_files/modem/mmode/ue_usage_setting,1,01,1

You can use the following command to disable VOLTE function:

 at+voltesetting=0
 at+cnv=/nv/item_files/modem/mmode/ue_usage_setting,0,01,1

SIM7600X makes a phone call and answer it on your phone
ATD131xxxxx816;

Record the sound of SIM7600 and mobile phone to the module memory E drive (change recording to memory card to D)
AT+CREC=3,"e:/rec.wav"   

End recording
AT+CREC=0

Play the sound to the mobile phone
AT+CCMXPLAYWAV="E:/rec.wav",1

Play the sound to the SIM7600
AT+CCMXPLAYWAV="E:/rec.wav",2

End playback
AT+CCMXSTOPWAV

If the text message is saved on the SIM card, the general limit is usually 50, and it can be queried through the command: AT+CPMS?

AT+CSCA="+8613800755500"

The command needs to be added with + Enter, return OK. Note: The SMS service center number for China Mobile is +861380xxxx500, where xxxx is the long-distance area code of your location. The SMS center may vary by place, and you can check it specifically by Baidu search or by calling the customer service of China Mobile or Unicom. This SMS center is in Shenzhen (0755)

• Confirm that the SIM7600X is registered to the network and that the SIM card can send and receive text messages normally on phones and other devices;
• Set the correct SMS center number;
• Initialize the SMS settings with the following commands:

AT+CSCS="IRA"
AT+CSMP=17,167,0,0

It supports SIM Standard cards, as shown in the figure below. If it's a Micro or Nano card, a card sleeve is required.

This issue is generally caused by poor contact between the SIM card and the module's SIM card slot.

Using USB 5V power supply, after successful networking, the current is generally in the range of 50~300mA, with an average of about 150mA (for reference only, depending on the network environment and networking working status).

If enabled simultaneously, average: 110~170mA

• Frequency: 700m 800m 900m 1710-1920M 2010-2100M 2300-2400M 2500-2690M-5800MHZ
• Gain: 9dbi ± 0.7dbi

Please put the jumper cap on C and connect the USB TO UART interface of SIM7600X to the USB port of a computer or Linux board such as Raspberry Pi through USB type-A to micro USB to send commands to debug:

SIM7600X mainly includes but is not limited to the following models:

1) The AUX auxiliary antenna is a diversity antenna. If the main antenna signal is poor, the receiving antenna is used to receive the signal. They are in different physical locations, so one will always be better. After connecting the diversity antenna, the bandwidth and sensitivity of the rate will be improved by about 20%.
2) It is not recommended to only use the AUX antenna. If the main antenna is damaged, you can also connect the AUX antenna to try using it. Diversity antennas allow the receiver to obtain a maximum diversity gain of up to 3 dB, but diversity antennas do not have transmission capabilities. Therefore, you need to connect the main antenna to transmit signals to the base station to register on the network, and only then will the auxiliary antenna take effect.

You can use the following command to check if there is a Qualcomm device. If the COM driver has already been loaded (which is usually included in Raspberry Pi systems), a series of ttyUSB * will also appear:

lsusb
ls /dev/ttyUSB*

Close the ModemManager process to prevent useless data from being displayed when debugging the AT serial port with minicom

sudo su
killall ModemManager

The details are as follows:

1) /dev/ttyUSB0-diag port for output developing messages
2) /dev/ttyUSB1- NMEA port for GPS NMEA data output
3) /dev/ttyUSB2-AT port for AT commands
4) /dev/ttyUSB3-Modem port for ppp-dial
5) /dev/ttyUSB4-Audio port

• You can initialize using the following commands:

echo "4" > /sys/class/gpio/export
echo "out" > /sys/class/gpio/gpio4/direction
echo "0" > /sys/class/gpio/gpio4/value
echo "6" > /sys/class/gpio/export
echo "out" > /sys/class/gpio/gpio6/direction
echo "0" > /sys/class/gpio/gpio6/value

• If using the Bookworm system, please use the py script to initialize the pin

Generally, it is the problem of baud rate, TTL level, and wiring, the details are as follows:
SIM7600X connect Arduino

• Without USB, some functions are restricted, and you can use AT command control and PPP to access the Internet at low speed using AT command control and PPP only by connecting UART through a pin header
• Because the communication speed of GPIO (UART) is very limited, if you want to achieve 4G high-speed Internet access, please connect to USB to realize point-to-point dial-up Internet access

SN is the manufacturer's production information, P/N is the module's version information; these codes are not fixed, used for distinguishing production information, and may vary between batches; users do not need to pay attention to them

• Ensure your system kernel is 5.4 or higher. Do not use sudo update to upgrade to the latest version on Raspberry Pi, as this will upgrade the kernel version to a level higher than the current firmware, causing it to be unrecognizable.
• It is recommended to use the more convenient RNDIS dial
• You can flash the latest Raspberry Pi Raspbian system and reconfigure the NDIS dial-up

The new driver may not be compatible with some Windows 7 systems; you can try using the old driver:

• SIM7600 old driver
• SIM7600 new driver
• Follow the steps below to install the driver:

1. Download the driver: SIM7600X driver file
2. Insert the 4G HAT as shown in the hardware connection diagram above into a Windows computer (taking Windows 10 operating system as an example in the following text)
3. Ensure the module is properly powered on
4. Open Device Manager ->Other Devices ->"SimTech,Incorporated" ->Update driver ->Browse my computer to find driver files ->Select the path where the driver files are stored based on the system ->Installation complete.

4. Install all detected devices according to the method mentioned above. The effect after installing the drivers is as follows:

You can refer to the below method, detailed steps are as follows:

• How to turn a Raspberry Pi Zero W into a 3G 4G router

1. Pay attention to check the device manager, the upgrade process will prompt the new device inserted, and the first upgrade will not have a device driver;
2. Pay attention to the USB cable, the USB cable rate is high during the upgrade process, so you need to choose a better quality USB cable to avoid poor contact.
3. Run the upgrade tool (SIM7500_SIM7600_QDL V1.41 only for Update) with administrative privileges
4. Uninstall and reinstall the update tool (SIM7500_SIM7600_QDL V1.41 only for Update)
5. For more operation details, please refer to this video: SIM7600 firmware upgrade

Please confirm that the file sim7600_4G_hat_init exists in the current directory

The general operation is: download the demo, unzip it, rename the c folder under the Raspberry folder to SIM7600X, and then copy the entire SIM7600X folder to the /home/pi directory on the Raspberry Pi Navigate to the /home/pi/SIM7600X directory via the command line, and then execute the chmod 777 sim7600_4G_hat_init command.

• Execute: autoreconf -vfi, then recompile, see the figure below:

No, modules can only be obtained passively, and the IP address cannot be actively modified