HL7800 Band Scanning Issues with Multi-IMSI SIM

A quick background: we initially tested a multi-IMSI SIM with the HL7800 in the US and connection times were fast (order of minutes). This was done with all the standard bands enabled and on CAT-M1 (LTE-M) (+KBNDCFG: 0,0000000000000808189F).

The network provider then tested in Serbia with the SIM card, where it seems only band 20 is active (also only NBIOT is available so they did manually set the RAT to NBIOT). They had tested with a larger set of bands (+KBNDCFG: 1,0002000000000B0F189F), and they found that the test took 4 hours to find the appropriate band to connect to.

After procuring the hardware required for the additional logs, a test was performed in Bulgaria where a new LTE-M cell was opened. So, we wanted to a test to see if the behavior was the same that we were seeing in Serbia with NBIOT, and just to test the logging. However, modem scanning times were longer than expected here as well and it was unsuccessful in connecting to the network during the testing period.

Since we are looking to do further testing to find out root cause of unexpected behavior, can you provide your input on the logs and setup?

Notes about testing:

  1. Configurations:

+KBNDCFG: 0,0002000000000F0F1B9F
at+cfun =1
+KGSN: 5N026442610810
+COPS: 0
+CGDCONT: 1,“IP”,“gigsky-02”,0,0,0,0,0,0,
+CGDCONT: 2,“IPV4V6”,0,0,0,0,0,0,

For the logs provided in the email, a few questions:

  1. Are these logs as you expected? Are there any recurring commands or any extra debug that needs to be enabled?
  2. Any changes needed in the configuration required?
  3. If all bands are enabled (0000000000000809181F), and a modem connects to one specific band (0800 for example) but then is moved to a region whether 0800 is not available in the region, what is the expected behavior?
  4. Is there a way to wipe the memory for any saved bands?
  5. Is there a command to see any available networks in range? Is there any way to enable outputs where it prints the bands being scanned?

Hi @nchow
Welcome you to our community
According to your description, I assume your issue now is that the HL7800 module can’t connect to network in Bulgaria so I will focus on it.
Please refer to below for my answers

  1. Please share with me the output of commands below:

  2. Temporary no needed

  3. If you leave the network coverage area of the module, it will loses network connection until you are in the coverage area, it will reconnect to the network.

  4. You can use AT+KBNDCFG command to set other bands

  5. You can use AT+COPS=? command to see available networks in range
    For more details about AT commands, Please refer to the document following the link below:
    HL78xx AT Commands Interface Guide

a. Which SIM card are you using in Bulgaria?
b. Has this issue happened before? Or is this the first time?