3G On Board Cell / WiFi - External Antenna Possibilities

What I'd Like to do:
Add an external antenna to the existing onboard Cell / WiFi Modem Device.

Why I'd Like to do it:
Use "WiFi" calling on my phones and extend data ranges. This would be as a substitute to adding a WeBoost type device.

Questions:

1. Where is this Cell / WiFi modem located? I assume behind the passenger Kick Panel?
2. What kind of plug does it use and can I get those plugs from a supplier?
3. What frequency does it operate on? Or is there somewhere I can go for the Tech-Specs?
4. Is there somewhere to get an external antenna or do I need to make one (I have RF experience with antenna theory and building)?
5. Where is the current OEM Antenna located? Last vehicle that had one of these still had that antenna in the cabin inside the sheet metal envelope, which is why I'm looking externally to improve reach.
6. Most importantly.... Has anyone done this yet and what was your results? Success / Failure? Would you do it again?

Many thanks in advance!

 

Is this the same as the DCM? Data Communication Module?