Not sure what network you’re on, or how long you’re going for, but on a recent trip I was able to use my inclusive ‘free’ call minutes (no roaming costs at all) on the 3 network in Australia (same in Hong Kong). I received calls too and didn’t have to pay any roaming charges either (I was still within my monthly limit). I’m with 3 here on a pay monthly plan with a ‘free’ text add-on, didn’t have to pay anything extra to send texts either. So when the bill arrived it was just the typical amount, despite having used the phone a lot in Oz & HK. I did have to keep an eye on the phone latching onto other networks (I suppose the other network signal may have been stronger at times) but could re-connect to 3 easily enough.