Hong Kong version of iPhone5(iOS 10.3.3) uses a telecom card, which can be 4G, but the signal is 0, so you can't make phone calls or send text messages. Try to solve it.

I tested this scheme myself, and I successfully tested it at 10.3.3. First, restore the network. I am restoring the settings directly. Because previous attempts to restore the network failed. . . . . . Step 1: Insert Unicom card, turn off wifi, input data, turn off 3G and turn off data roaming. After I clicked on it, it flashed, and then it appeared. Welcome to Unicom. After that, it was a 3G network. Before the network was restored, it was gprs, but it may be that the display problem has little effect. Then pull out the card directly and insert the telecom card. Then I found that Bluetooth was on. I turned off the Bluetooth conveniently, and I don't know if it has any influence. Then I showed no service. I went into roaming to find CDMA, and clicked off-on-off three times. I turned it off three times because it was on by default. Then I turned on data roaming, waited for more than 20 seconds, and then there was a telecom signal. Then I turned on wifi and used it normally. I heard that if you insert Unicom card again, it will be cracked again.