All the information you need can be obtained from Pakistan Software Export Board (www.pseb.org.pk). I have worked there for the past year and this is the agency directly resposible for promoting IT exports.
Although there are many means of setting up a call enter in Pakistan, the main issue here is getting reliable and cost effective bandwidth (currently PSEB provides banwidth @ USD 3000/MB). In the area of software there are many solutions available like CIsco Call Manager and other foreign vendors. Som local companies have alsoe developed and implemented call center management solutions like 2b Technologies and e-Tel.
Let me know if you need more help in any area related to IT business in Pakistan. Hope the above info helps you out.