When someone calls and you’re already on a call, you will see the call alert window on your screen. You can choose to Answer, Answer with video or Decline the call. If you decide to answer the incoming call, the current call will be put on hold. To take the call off hold, click Resume call in the call toolbar.
                    If you want to, you can add 
                      the incoming call to the call you are already on. Or 
                      you can transfer 
                      the incoming call to another number.
                    If you have Skype Credit 
                      or a subscription, you 
                      can set 
                      up call forwarding to forward incoming calls to another 
                      number. To set up call forwarding, in the menu bar, click 
                      Tools > Options. Under 
                      Calls, click Call forwarding.
                    If you have voicemail, 
                      you can choose when to send calls to voicemail. You can 
                      send calls to voicemail if:
    - You do not answer within a certain amount of time.
- You reject the call.
- You are already on a call.
To set up voicemail, in the menu bar, click Tools > Options and under Calls, click Voicemail.