text iphone no data

my husband has an iphone 5s as a pay per use phone on bell aliant . He does not have a data plan but is supposed to pay 60 cents per text message and per call. he hardley sends a text . when he is on wifi he can send and receives imessages no problem .

i have an iphone xr today i tried to send him a text . He was in hospital and had no wifi

it kept sending as imessage and of course not being delivered it remains as blue and never goes to green bubble . Can someone please help me set his phone so i can send him a text