Session Initiation Protocol (SIP) has already been accepted as the multimedia control signaling standard in ubiquitous wireless network by IETF and 3GPP etc. However, the handover procedure with SIP suffers from undesirable delay for real-time multimedia applications in WLAN. Moreover, the existing handover management protocols are not sufficient to guarantee handover of VoIP session in WLAN. In this paper, a cross-layer handover management architecture (CHM-SIP) is developed to shorten the service interruption time when the mobile node frequently handovers between subnets of WLAN. Based on this architecture, the detailed design of a cross-layer handover management for Voice over WLAN (VoWLAN) based SIP is carried out, which uses mobile's speed and handover signaling delay information to enhance the handover performance. The theoretical analysis and simulation results show that CHM-SIP significantly enhances the VoWLAN handover performance.Index Terms-VoWLAN, handover management, SIP, crosslayer protocol design I.