If you have Wi-Fi but no cellular reception, you can still send and receive messages:
: Enable this in Settings > Cellular > Wi-Fi Calling to send traditional SMS (green bubble) texts over a Wi-Fi network. Troubleshooting Poor Reception If your iPhone isn't receiving texts despite having signal: Connect to a satellite with your iPhone - Apple Support iphone reception
For a more accurate reading of your reception than standard bars, you can use : Open the Phone app. Dial *3001#12345#* and press Call . If you have Wi-Fi but no cellular reception,
: Open the Messages app; a prompt to "Use Messages via Satellite" will appear automatically if you have no signal. iphone reception