Robust and accurate positioning techniques with seamless integration between indoor and outdoor environments have been receiving considerable attention for applications of location-based services (LBSs). Regarding positioning systems based on wireless network services, the location inaccuracy is caused by radio signals being jammed and/or shielded in outdoor environments and reflected and/or attenuated in indoor environments. As wireless positioning systems do not provide customers with adequate accuracy, inertial sensing positioning techniques can be used to deal with the inaccuracy problems for LBS applications. Consequently, in this study, we obtain displacement information by the relative positioning techniques according to the dead-reckoning (DR) approach to estimate the location of a mobile device (MD) for indoor and outdoor environments. Furthermore, instead of an MD mounted on a fixed place on a human body, the inertial measurement unit (IMU) is taken as a handheld MD (such as a smartphone) for positioning systems. In terms of the approach combining the DR algorithm with the heading and delta-velocity information extracted from an IMU sensor, the experimental results demonstrate that the positioning technique can recover and operate in a short period of time as the radio-based approaches cannot provide tailored accuracy for real-time LBS applications.