If someone texts me internationally would I have to pay?

I have a friend from uk. I live in us. We both have iPhones so we usually iMessage but for some reason my iMessage was off so he send 4 texts to me as regular text messages. Would I have to pay for him texting me?

Added (1). I didn't respond to the texts btw

I would suggest downloading Viber or some other free calling/texting app if you are unsure.

Yeah you would