Receiving one long text message that shows multiple on data usage

some phones and carriers only allow texts to be certain number of charactors, when my sister on tmobile sends me a super long text it sends from her phone as 2,3 and sometimes 4 texts but arrives as 1 on my iphone but im not sure why texts would use any data

It’s not using the data, it’s just showing multiple texts from the number when I’m only receiving one. Basically my girl thinks I erased texts when I didn’t because it shows multiple on our AT&T plan. Im trying to prove to her that I’m not lying , which I’m not 

AH show her this thread this is how it works and is normal

Thank you very much!!

@Constructive It’s not just some carriers, it’s all carriers. The SMS protocol has a 160 character limit. Phones are just smart enough now to break them up and reassemble automatically so it looks like one long message. Anyone still using an old dumb phone can only send 160 characters at a time and if they receive a multi-part message, they receive them individually.