Are iMessages free when using Wi-Fi even with international numbers?

I'm from the USA so I have a US number, but I'm currently in Australia.
I brought my iPhone with me to use with Wi-Fi.

My friend here in Australia has an iPhone (clearly with an Australian number), if I send him a message using iMessage (while I have Wi-Fi), will he be charged because my number is international (& vise versa for if he replies)

No. Using Wi-Fi it is free either way.

  • Why is my Iphone not sending as Imessages and receiving iMessages from one person? I'm texting my wife and we both have iPhone's and she is getting the messages as an iMessage but the ones I'm sending her on my end show up at green. Sometime it will go as blue, get the little red exclamation point then send as regular SMS. I'm texting someone else too and she has an iPhone, and she is getting mine as regular iMessages and mine are sending as regular iMessages. Why aren't they sending to me wife as iMessages?
  • Using an old iPhone with international sim? I'm going to be studying abroad in Ireland from January through May of this year. I just got a new iphone 8 last week and I still have my old iphone 6. I was planning on keeping my iphone 6 so I can use an international sim to get phone calls, data, etc. Since I've already activated my new phone and taken my old phone off the account, will I need to call verizon and have them unlock my old one(iphone 6)?
  • Using an international SIM card for an iPhone? I'm studying abroad in the fall for almost 4 months and will be putting my phone to "sleep" at a cost of $10 a month here In the states. I want to buy an international SIM card for when I arrive in Italy so that I don't have to put a new phone in Italy. Does anyone know the cost and what is included in buying an international SIM card. The fee in mins, where can I call, texts, Internet, can I still use Wi-Fi? Serious answers only.
  • Is there any App that sends free international text messages on iphone? Is there any appstore app guys, so that i can send free international text messages, or is there any free international text sending website?