4 Use Wi-Fi Calling
Image via Apple Support
Wi-Fi calling basically allows you to use your home Wi-Fi network to place calls, a bit like a wireless VoIP option. If you get poor data and signal reception, your Wi-Fi could be a much better option.
Most major carriers offer the ability to switch to Wi-Fi calling right on your device. But it may cost extra, so contact your carrier for details.
Head to Settings > then tap Phone. The Wi-Fi calling feature is typically located here. And remember, this setting works best if you have a strong Wi-Fi signal with plenty of bandwidth.