Thank you for the reply.
Yes, "Skip if in use" is unchecked but problem still persists. What happens is that when I'm on call with someone and if I get another call -and if I press talk on the phone to pick up the second incoming call then first one goes on hold as expected , then I hear an announcement from Anveo system that press 1 to accept the call or press 2 to send the call to VM. Even if I press 1, second incoming call goes to VM, while first one is still on hold.
Just FYI, I have Personal Unlimited phone number plan + FREE subscription package.