Dear Atif,
I am the Chief Technology officer of an international call center here in Islamabad.
BTW I think Krarchi is a great choice for setting up a call center because your overheads are much lower and the PIE network touches the global network without any hop!! Plus HR costs are lower on average.
Islamabad is great because the telco infrastructure is reliable and you get good neutralized accents. Let me know if you need help