Why can't I make or receive calls on my iPhone 5S?

[iMore Question]

Can't make or receive calls on iPhone 5S

When I receive a call from a certain person, it goes straight to voicemail for him. Even if I try to pick up the call. Mine to him go straight to voicemail.

 

[kch50428]

Re: Can't make or receive calls on iPhone 5S

Is his number blocked on your phone? Your number blocked on his?

 

[Amia45]

Re: Can't make or receive calls on iPhone 5S

it sounds very strange