sprint phone -block an incoming call

Hi,

I have a sprint phone.

I am able to send and recieve most calls with no trouble, however there is one person that I am able to text message, but unable to call. When I call the same # that I text, I get a recording saying that the # is inaccessible.

I know how to block a #, but can you block an incoming call? Is this what's happening here?

If not, any ideas on how to troubleshoot the phone? I was on the phone with sprint for hours last night, but they told me that my problem "wasn't possible."

I'm hoping cnet readers can do better.

Thanks for your help.