I have tried the same sim card on the Adafruit Fona 808 on both the raspberry pi 3 and the arduino uno. Neither one registers and says that signal strength is 0. I have the recommended quad band antenna attached and the device reads the sim card correctly but I never get a signal. I use verizon for my personal carrier and as I understand it hologram piggybacks on those networks. My personal signal is strong but every time AT+CSQ reads 0,0 and AT+COPS=? returns (0-4),(0-2).