Is it free to send Hangouts messages from S. Korea to the U.S.?

[pquirk777]

My son recently transferred to South Korea and purchased a local iPhone. We've always been an Android clan so we were looking into Hangouts for iOS to message each other. However, we want to know if it is free to send Hangouts messages from S. Korea to the U.S. over a cellular network?

 

[kch50428]

any message service other than carrier-provided SMS text messaging uses data - and data would be subject to any cap under the service contract - otherwise, there should be no additional charges.