The W1209 can be turned into an MBIM device with the same USB message as the W1208. It then changes its device ID from $4000 to $4004. This should be preferred due to RNDIS being deprecated.

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The last update of the data package was in 2019. What's the release schedule for further updates? Does anything need to be done for a device to be included besides posting configuration data in the "Device Information" forum?

The 4G Systems XSStick W1209 presents as a mass storage device with vendor ID "2fd4" and device ID "4000". The Windows tool switches it to modem mode, which presents as vendor ID "2fd4" and device ID "4001". This mode switch can be replicated with usb_modeswitch -v 2fd4 -p 4000 -V 2fd4 -P 4001 -M ...