Phone rang twice, then went to voice mail- why?

Anonymous
I was calling someone's cell phone, and it rang twice before going to voice mail. Normally it rings far more than twice. Why'd this happen?
Updates
+1 y
Okay, I'm pretty sure I've figured out he ignored my call after 4 of the same answers haha. Thanks!
Updates
+1 y
Never mind, 5.
Phone rang twice, then went to voice mail- why?
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