This work design and implement a User-oriented Handoff Control Framework (UHCF) comprising Wireless Sensor Networks, SIP and VoIP. A two-stage strategy is proposed to support user-oriented handoff. The strategy is to detect and collect user's location information, and determine whether user-oriented is triggered. If a user-oriented handoff is triggered, then a progressive VoIP session is switched smoothly from the old to the new host with the user's mobility. We also implement User-oriented Handoff Control Framework (UHCF) to a SIP-based VoIP system. Implementation results show that the UHCF with SIP-based VoIP service has deployed successfully by wireless sensor networks, and the system can efficiently assist user-oriented handoff with VoIP service.