This document specifies the Session Initiation Protocol (SIP) P-Refused-URI-List Private-Header (P-Header). This P-Header is used in the Open Mobile Alliance's (OMA) Push to talk over Cellular (PoC) system. It enables URI-list servers to refuse the handling of incoming URI lists that have embedded URI lists. This P-Header also makes it possible for the URI-list server to inform the client about the embedded URI list that caused the rejection and the individual URIs that form such a URI list. This memo provides information for the Internet community.