-> Hardware is not detecting the Modem. 

[admin@Branch: versa] $ lsusb 

[admin@Branch: versa] $ usb-devices 

If the above Output doesn't show a Modem either by Sierra or Quectel, it means the Hardware is not detecting the modem. 

Steps to recover:  

1) Check if the Hardware is LTE capable. You can do this by checking the model No. of the Hardware. 

2) Power down the hardware by removing the power cable, Wait for 10-15 seconds and re-connect the power cable. 

-> VOS is not detecting the modem. 

If "mmcli -L" doesn't show a modem, and "lsusb" shows the Modem being detected: 

[admin@Branch: versa] $ mmcli -L 

No modems were found 

Steps to recover:  

1) If "usb-devices" SHELL command does not show an output like Sample-1, this means the modem is stuck in bootloader mode. 

2) If this is the case, remove the power cable and reconnect back, but this would be a very rare case to occur. 

The sample for a functional LTE modem is Sample-2, shown below. 

_______________________  

Sample-1:

T:  Bus=02 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#=  2 Spd=5000 MxCh= 0 

D:  Ver= 3.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS= 9 #Cfgs=  1 

P:  Vendor=1199 ProdID=9071 Rev=00.06 

S:  Manufacturer=Sierra Wireless, Incorporated 

S:  Product=Sierra Wireless MC7455 Qualcomm® Snapdragon™ X7 LTE-A 

S:  SerialNumber=LQ94237102031028 

C:  #Ifs= 5 Cfg#= 1 Atr=a0 MxPwr=504mA 

I:  If#= 0 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=ff Driver=option

_______________________ 

Sample-2 [Functional] 

T:  Bus=02 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#=  2 Spd=5000 MxCh= 0 

D:  Ver= 3.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS= 9 #Cfgs=  1 

P:  Vendor=1199 ProdID=9071 Rev=00.06 

S:  Manufacturer=Sierra Wireless, Incorporated  

S:  Product=Sierra Wireless MC7455 Qualcomm® Snapdragon™ X7 LTE-A 

S:  SerialNumber=LQ94237102031028                  

C:  #Ifs= 5 Cfg#= 1 Atr=a0 MxPwr=504mA 

I:  If#= 0 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=ff Driver=option

/usr/bin/usb-devices: line 79: printf: a: invalid number                      

I:  If#= 0 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=ff Driver=qmi_wwan   

I:  If#= 2 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=00 Driver=option  

I:  If#= 3 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=00 Driver=option  

I:  If#= 8 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=ff Driver=qmi_wwan

3) Incase the modem is in MBIM mode and not in qmi mode, please follow this step.

https://support.versa-networks.com/a/solutions/articles/23000025752

the P.S.: LTE Modems must be shipped in QMI mode from white box'sFactory.

4) The modem is in Hung state. 

If the above 3 steps don't hit, then the modem is likely in a hung state. Please try the below and check if we can output or TimedOut. 

***Try this command for 2-3 iterations***

[admin@versa-flexvnf: ~] $ qmicli -p -d /dev/cdc-wdm0 --uim-get-card-status 

Timeout 

Steps to recover:  

1) Power off the hardware by removing the power cable, wait for 10-15 seconds, re-connect the power cable. 

+++++++++++++++++++

Can I use the second SIM slot in any of the CSG devices?  

If the device model is 2LA/2LB, then, yes. If it is not, for example: WLA/WLB/LA/LB, then we cannot use the second SIM slot.