Sent as text message/Overseas

Hello guys,

I am currently in Italy with a boost contractcand using an Iphone S. My wife blocked my # and the texts are sometimes going through as : sent as text messages and are green. I have no boost coverage here so no phone signal of any sort. My iMessage is on and texts too so example i can text other friends with iphones 📲, no problem. When I text on the blocked number the message go blue shows the time but then a blue line scrolls up in the screen.... and the message is green with a !! In red. Funny thing if i swap from a router to an hotspot sometimes goes through again in green and as a text message. My question is: where is it going? Texts are going through the wifi to the other blocked phone or I'm just delusional lol..

Thanks all.