iPhone 6S No Service but SIM can be read and Modem Firmware is visible
I don't think it's a problem with the SIM reader. I tried a working Verizon one and it called fine when I turned on WiFi Calling, but it still showed Searching and then No Service. If it was a baseband IC chip problem, wouldn't the Modem Firmware be unavailable? Earlier today, I turned off Airplane Mode for whatever reason since I always keep it on and the Verizon text actually showed up with about 3 bars and went back down to No Service within a minute; I've never seen it do that before.