I don't have an iPhone but found this info from Apple which may help
"You might not be able to get SMS or text messages that someone sends you from an iPhone because they're still being sent as iMessage"
Do read the complete article though...
Best of luck and welcome to the forum
Veritas Numquam Perit
I don't think he has your number saved as an iPhone.
He can edit that in his contact card for you.