My property is underground with a purpose fitted faraday cage and mobile signal (or radio or tv for that matter) cuts off as soon as you go in. I’m not worried about the phone but I wanted a simple to fit 4/5G router thingy so I bought the one in the attached link. It is hassle free and covers the whole property no problem (obviously not outside as the faraday cage works both ways), I have a Voda SIM card and this thing will run several things at once including an HD tv. It’s power consumption is minimal (I’m off grid). Another idea in the pot.
https://www.ebay.co.uk/itm/TELTONIKA-RUT955-DUAL-SIM-3G-4G-LTE-M2M-ROUTER-with-RS232-RS485-GPS-UK-version/172976694046
