You should always ensure that your recipient is ready to pick up the phone by either letting them know ahead of time that a call is on the way, or knowing that they are available. Once the call is answered, the recipient must press 1 to connect to Santa following the elf's invitation.
If the recipient does not press 1, or if their voicemail service picks up for them, this will use up 1 of 3 attempts you have to place the call.
NOTE: If you schedule a call, the time zone used is your current time zone.