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That would depend on how you have your call forwarding set up. If you have call waiting set up to give you notification that someone is trying to call you before it is forwarded to voicemail, then the number will be in your call log. Otherwise, it will go through to voicemail, where you should normally get an SMS notifiying you that a call went through to voicemail, along with the number (if they are not set to "private").
Never be afraid to back yourself when trying new things, just always make sure you have 3 escape routes if things go wrong.