my galaxy s4 won't receive texts from iPhone users?

[AC Question]

I got a galaxy s4 about a year and a half ago (love the phone by the way) but I have always had a problem with texting iphone users. When they text me I could get it immediately or I could get it in a couple of hours or not at all. This is very bad because my friends think I'm ignoring them. I have no problem texting non iphones. I can text some iphones more reliably than others. I have never had an iPhone by the way so I can't sign out of imessage like everyone suggest. What do I do?

 

[dpham00]

Which carrier are you using?

 

[Joseph Smith12]

I have t moble