If a call goes to voicemail when using a free call - yes, you lose that call. Free calls are counted upon hitting the "SEND" button. If you're calling using tokens, you are only charged a token if your call is answered. If you are charged a token for a call that goes to voicemail, hit the "Issue with Call" button and forward the problem to customer support. They should award you a token after reviewing your call.
We regularly monitor calls that go to voicemail but still charge a paid token and will return the token within 24 hours.