Siemens plc ETSI TISPAN has presented Next Generation Network (NGN) requirements for the delivery of two identities for the caller and two identities for the callee in a SIP INVITE-initiated dialog. Although the solution for this in SIP is relatively straightforward for caller identity, the delivery of callee identity presents some additional problems. This document discusses the issues and suggests some candidate solutions. This work is being discussed on the sip@ietf.org mailing list.