Operators and wireless internet service providers are increasingly using Wireless Mesh Networks (WMN) to offer Internet connectivity, as it allows fast, easy and affordable network deployment and provide Internet services to the end user through all existing network technologies like Ethernet, WLAN, WiMAX, GPRS etc. Due to evolution of 4G heterogeneous wireless networks, today's mobile devices are equipped with multiple network interfaces. However, when an end user having these mobile devices moves across heterogeneous networks, the previously established communication may no longer remains active. We proposed the vertical handover management mechanism for a distributed IP based mobility management protocol (DIMMP) in WMN to provide seamless mobility with service continuation for mobile devices. Simulations were performed using NS2. Results show that handover delay is reduced significantly by DIMMP in comparison to MobileIP.