As per HEC Pakistan, if u have 18 years of education with one year research work either MPhil or MS, you will definitely go for Phd in any recognised university after clearing your NTS GAT subject paper and the minimum duration of Phd will be of 3 years. Same 18 years of degree is required for Phd abroad either you go at your own expense or through HEC scholarship. PhD from abroad ( USA, Australia, Europe ) will definitely give you a competitive advantage towards leading and you can also enjoy better salary packages here. I will suggest you to plz go through MPhil in business management before going for PhD as it will build your approach towards better understanding of research process, case studies carried out and critical writings which will certainly helpful for your PhD.