The ability to provide handset tracking or positioning system independent from the available commercial mobile network is required in emergency. In some cases, it is possible that the commercial mobile networks are suspended due to the natural disaster, terrorist attack or other emergency condition. The commercial mobile networks might also unavailable in the remote areas where some extreme sports or research exploration take place. During emergency evacuation, detecting handset location might be a big help for the rescue team to loacte the victim. This work analyzes the system architecture of OpenBTS and AirProbe GSM-Receiver, and proposed a way to achieve affordable mobile phone positioning with these open source platform. The target is to build a cost-effective prototype which able to detect handset position more precisely. An effective approach to increase the positioning accuracy is also presented. The result from this paper can be used as a reference of how to develop a cost effective mobile positioning system.