What are wireless web messages? According to a Sprint CSR I spoke to, wireless web messages is same as SMS. Now we all know to never trust everything a Sprint CSR tells you so what are they?

Anyway I have unlimited vision since when it was first offered by Sprint for $10/ month. I've been monitoring my account on Sprint's website and noticed a new entry named "wireless web messages" and that they are unlimited. I have been sending SMS in the last week and noticed the number of wireless web messages has been increasing. So the big question again: If wireless web messages are not SMS then what are they?