The business world of today is highly competitive. Business users demand IT organizations to adapt quickly to changes and provide on-time, cost-effective solutions. This compels companies to took closely at their software development processes, to improve them and remain cost-effective. Offshoring is a well-known cost-effective solution for projects that follow waterfall and other traditional software development life cycles (SDLC). Waterfall SDLC may not be ideal when requirements are changing rapidly. Achieving rapidness in software development along with offshoring will enable companies to provide quick and cost effective IT solutions. To manage rapidly changing requirements, a large telecommunications company moved out of traditional waterfall model and adopted Extreme programming (XP) software development methodology. This paper discusses, in detail, a Telecommunication software project case study along with the customized XP onsite-offshore model that was successfully used in developing the project. This paper also share the lessons learnt from this XP onsite-offshore model.