I just realized today: without wifi and data, I could send the text message out, but I couldn’t receive the text message, is this normal for the PM? Or something wrong?
@Lehaha likely your friends are sending you iMessage or RCS. Since you are not receiving, it's a sender issue as they choose to send you with iMessage/RCS.
FYI, you can tell if they are iMessage/RCS or regular SMS
Sounds like an iphone. Turn on send as sms and send as mms. Send and receive from a phone number, not an email address.