I am using the data network to iMessage and not on wi-fi so I am wondering if it is still free or if I will incur charges?
Staying connected while traveling overseas is important. iMessage is a great way to send messages using either Wi-Fi or cellular data. iMessages cannot be sent as text and require an internet connection to be sent. So it does use a small part of any data allowance you have.
Here is a link to more details: https://support.apple.com/en-us/HT207006
Let us know if you have any additional questions.