Hi,
Yes, you definitely can! When you get to your new location, make sure to join your Echo device to the local WiFi, and then you should be able to make calls!
To join your Echo device to a new location’s WiFi, follow these steps:

1. Open the Alexa App .
2. Select Devices .
3. Select Echo & Alexa.
4. Select your device.
5. Select Change next to Wi-Fi Network and follow the instructions in the app.

If you don’t see your Wi-Fi network, scroll down and select Add a Network (for hidden networks) or Rescan.
Once you’re joined to the new WiFi, you can use your Echo device the same way you would at home!

I highly recommend a travel router. They are especially convenient if you have more than 1 or 2 devices to connect.  All your devices can be setup to autojoin the travel router so you only have one device to connect to a new hotel or other network. It also provides a much more stable wifi connection and a buffer between your devices and the public wifi.
I use the GL.iNet GL-AR750 but TPLink and RAVPower also have good offerings.