Using the TMobile ISP Box sim in a Netgear LB1120

Call Me Bob wrote:

You CANNOT use the SIM from inside the gateway.

As long as the device you are transplanting it to has the same IMEI, you absolutely can.  I use a Mikrotik RB and a Quectel LTE modem (see my posts above), which I now have working.

Ret60sp wrote:

The TMobile ISP box does NOT have a bridge mode and it does NOT have external ports for external antennas.

TMO's major limitation is that even if you do get a gateway device with bridge mode (or any other NAT function), TMO's CGNAT implementation makes life difficult.  Possible solution = OpenVPN on a $2/mo VPS.

Ret60sp wrote:

So I prefer my Mikrotik router, and my Mikrotik AP’s standing alone on the network.

I recommend you try my solution above if you like Mikrotik (I used the smallest board, but there are several other options).  Works great and the management across my network is consistent and easy if you are already familiar w/ Mikrotik.  Also, there are many other modem choices out there depending on what bands and technology (LTE / 5G) you wish to accommodate (and your budget, of course!).