got my iphone 5 on sept 21st and haven't been able to receive text from one person, he has virgin mobile and i have verizon, i've gotten them from everyone else, i'm able to send texts too
i recently switched from virgin mobile to verizon
i've called verizon and they said there isn't a problem
i've called virgin mobile and they don't have a problem either
If you are in his contact list, have him check the number saved in the contact. Sometimes external contact sources can modify numbers to an extent where the number format becomes incompatible with the system, for example, facebook sometimes adds a "+1" in front of a number.
Could be something wrong on the other persons end...this one is hard to call if it's only happening with one number. Are the text long (longer than 140 or 160 characters)? Try asking them to sending a short one (just type "testing" and send it)...see if that goes through. I would lean more towards the issue being on their end if you're saying you can send them to him fine...you're just not receiving them.