We completely understand that many customers want to pull of the ultimate surprise and so do not want the celebrant to be called before delivery and we have tried to oblige this request but after a few scenarios like celebrant not showing up to work, walking away from phone for 30 minutes plus or not picking numbers they don't know we reached a compromise that works operationally.
We call ahead the receiver on the day of delivery saying we have a package to deliver without saying who we are and what we are delivering. We ask them to expect us and keep their phones close.
If the receiver cant be reached on the phone, the buyer will be notified. (We take all these steps to ensure we avoid a situation where a delivery driver is kept waiting for more than 10 minutes).