MSR series router Telecom IoT card 4G dial-up Current Service Status is Limited, the terminal cannot obtain the IP address

The customer purchased a batch of equipment of the same model and needed to use a 4G card to access the network. The old equipment on site and the old version (R0306P11) could dial up successfully without any problem, but the new router (new router factory version R0707P21) could not obtain the address normally. 

 1. Premise: Customers can use old equipment to dial normally and have no arrears. This card has no problem in cross-testing on several old devices on site, but it does not work on all new devices. The configurations of both sides have been adjusted to the same and tested. 

 2. After upgrading the previous version to 0809P34, the fault remains the same, the Current Service Status is Limited, and the SIM Status is OK.

The interface status is protocol up and the physical status is down.

E-Ch1/0:0            DOWN     UP(s)        

Eth-channel1/0:0 current state: DOWN

Line protocol current state: UP(spoofing)

<h3c>display  cellular 1/0

Cellular1/0:

Modem State:

  Hardware Information:

    Model: U9300C DGNC

    Manufacturer: LONGSUNG

    Modem Firmware Version: QB30031.1.3_MX11(0125_3.1.1_L0328)

  Network Information:

    Current Service Status: Limited

    Registration Status: Denied

    Current Roaming Status: Roaming

    Current Data Bearer Technology: Unknown

    Network Selection Mode: Automatic

    Current IP address Mode: Cellular-alloc

    Current IPV6 address Mode: Unknown  

  WCDMA related info:

    Current RSSI: -73 dBm

    Current ECIO: -12 dBm

  Modem Security Information:

    PIN Verification: Disabled

    PIN Status: PIN Requirement Disabled

    Number of PIN Retries Remaining: 3

    Number of PUK Retries Remaining: 10

    SIM Status: OK

Network registration failed:

Generally, when encountering this kind of problem, execute display cellular. When the network is successfully registered under normal circumstances, the following is displayed:

3G：

Current Service Status = Service available

Current Service = Combined or Packet-switched

Packet Service = Attached

4G：

Current Service Status = Service Available

Registration Status = Registered

Current Service = Combined 或者 Packet-switched

As long as any of the displayed information is inconsistent with the above, it means that the network registration has failed, for example:

Current Service Status = Limited   //Or no service

Registration Status = Searching

The general troubleshooting methods for such problems are as follows:

1. First confirm whether the SIM card status is in good condition, which can be seen through display cellular: 

    1) If the PIN Status is not Ready, you need to enter the PIN code to unlock, and you need to contact the operator for unlocking. 

    2) If SIM Status is not OK, please reinstall SIM. 

    3) If the SIM card is confirmed to be installed correctly, please confirm whether the SIM card matches the format supported by the modem. For example, if a WCDMA modem is inserted into a China Telecom (CDMA operator) SIM card, it cannot register with the network. 

    4) When the SIM card status is incorrect, you can insert the SIM card into a mobile phone with the same modem format and test it to confirm whether there is a problem with the SIM card.

2. The mode supported by the SIM card is inconsistent with the mode currently set by the modem. Please check the current setting mode:

    3G：Network Connection Mode = WCDMA precedence

    4G：Technology Preference = No preference specified (AUTO)

    You can modify the working mode of the modem using the mode lte command in the Cellular interface view.

3. Connect to the VPDN network. If some parameters such as APN, authentication method, user name, and password are incorrectly configured, network registration may fail even if no dial-up is initiated. 

4. If you have just started the service, there may be a problem with the SIM card, causing the VPDN network to be abnormal. In this case, please contact the operator for troubleshooting. 

5. Execute plmn search to see if there is a network available and supported by the SIM card. 

6. Please check whether the SIM card is in arrears. 

7. Use the display cellular command to check the signal strength. Poor signal may also cause network registration to fail. 

8. Are 2 antennas connected to the 4G module? A customer connected an antenna and received the secondary connector. He was unable to register the 4G network. He could register the 3G network.