Pennsylvania AO 399 Waiver of the Service of Summons is a document that allows a party to waive their right to be served with a summons in a civil action. This document is filed with the court in order to waive the service of a summons. The waiver must be signed by the party or the party's attorney. There are two types of Pennsylvania AO 399 Waiver of the Service of Summons: Waiver of Service of Summons By Defendant and Waiver of Service of Summons by Plaintiff. The Waiver of Service of Summons By Defendant is used when a defendant waives their right to be served with a summons. The Waiver of Service of Summons by Plaintiff is used when a plaintiff waives their right to serve the defendant with a summons. Both forms must be signed by the party or the party's attorney and filed with the court.