Info needed for setting up a call center

Salam everyone.

I am an IT professional and has worked in US as software developer for almost 5 years. I have just relocated back to Pakistan and planning to setup an IT business. Call centers seems to be the talk of the town here in Pakistan among the IT related people so I am thinking to setup a call center here in Lahore. For that, I need to get some sincere advice, info and help from people who are already in this business and want to help the new entrepreneurs like me. Any help/advice in this regard will be greatly appreciated.

Here a few general questions which I would like to ask.

1. What type of Call centers (inbound, outbound etc.) are doing good business in Pakistan and where are their clients based?

2. Is it advisable/recommended to join a call center as an agent or some other HR position and try to understand different aspects of this business before starting my own Call Center?

3. What is the way of some existing Call centers to approach the new clients? Is the marketing done through online (internet) resources or are there any agents in the Call Center market who provide business to the call centers?

4. Is there any concept/culture of subletting the work (from big players to small/newer call centers)?

5. What are the major risks/threats to this busines which the owner should be aware of before setting up the business.

Many Thanks.