Can you try searching for networks manually and there select Verizon, T-Mobile or AT&T in the list. Verizon should be the top choice, followed by T-Mobile.

You can also test this & if you have the opportunity to connect somewhere to wifi with the internet. And check if you have a system update to do. If so, do it, and be ready with your pin code.

Under Network mode, select 3G only. And test that .

It's always good to make sure you have the latest software.As well as apps in the playstore. As apps are also relevant to Android's functions.

Keep in mind if you are going on a cruise, they may have their own mobile network via satellite which can be expensive when the mobile connects to it, and good to avoid. So a good Wi-Fi wireless network is good to find when you are out on a trip.

Also to preserve your surfing pot, so it doesn't run out too soon. So Wi-Fi is great to use as much as you can.

/F

@Jaha46 Hello,

just to check with you - when you didn't have the possibility to make phone calls, were you connected to the AT&T network? Does it work better if you connect to T-Mobile or Verizon? 

From what I noticed when I was in the US a couple of weeks ago, the issues was mainly with AT&T and VoLTE didn’t work as expected with them, which caused this issue. 

The tip from @frodrik91 to select only 3G is a great one, although it might give you issues with coverage in some parts of the country since they are closing down their 3G-networks rapidly. Also, this options is not available on newer iPhones.