To use the USB modem in an ESXi environment. You might need to check the following:

[root@localhost:~] /etc/init.d/usbarbitrator restart
usbarbitrator is not running
UsbUtil: VmkuserCompat_PClose in UpdateDeviceNamesfailed, reason: Bad file descriptor
UsbUtil: Attempting to reserve for VMkernel USB adapter(s): vmhba32
usbarbitrator started
[root@localhost:~] esxcli hardware usb passthrough device list
Bus Dev VendorId ProductId Enabled Can Connect to VM Name
— — ——– ——— ——- ————————- ———————————–
1 3 424 4030 false no (passthrough disabled) Standard Microsystems Corp.
1 4 114f 1234 true yes Wavecom Fastrack Xtend FXT001 Modem
[root@localhost:~] /etc/init.d/hostd restart