In the iPhone is possible use the network from another carrier to make/receive calls when your carrier is with no signal.
It's thankful to Wi-Fi Calling, but instead of use the Wi-Fi, use too the LTE network from the another carrier with signal.
Imagine if you're traveling to place where your carrier doesn't work, but you have a SIM Card from another carrier. With that, you can be able to make/receive calls using this another SIM Card, while you continue receiving calls with your native carrier.
That's very useful for me and I'd like to see it soon. So, I hope the Samsung could bring it in a future update.
I think you didn't read what I've wrote.
This feature allow me make/receive calls over the second carrier network, EVEN WHEN THE PRIMARY NETWORK HAS NO SIGNAL! That's very different.
If you're traveling you need to use the roaming and pay expensive taxes, when iPhone uses could just use the "Wi-Fi Calling using Cellular data" function to, at least, make/receive calls using their native carrier.