NetModem can be installed silently by using a command line option when deplying remotely. However, this does not make it easy to deploy via a GPO. This simple workaround means you can deploy via a Group Policy installation script, with a custom MST file.
1. Follow the Silent Installation from here
2. Copy the .Reg and .MSI Client installation into the same folder.
3. Start Orca, and open the MSI file.
4. Click Transforms, then New Transform.
5. Go to the Properties section on the left hand side, then edit the CONFIG 'value' on the right from 0 to the full path of the .reg file you created in step 2. ie.
6. Click Transforms, then Generate Transofrm, and save the .mst file into the same folder as the reg file.
You can then deploy the netmodem client by using the Client MSI file and netmodem MST file (under advanced).
Once the client software has been installed, you will need to manually install the modem on each client workstation.