Couple months ago, I received a call from Karachi regarding long distance service. It really inspired me to take that offer and I did. I have absolutely no problem with that service. Their customer service can be comapred with any US based customer service. I see no reason of failure of call center in Pakistan where labour cost is extremely cheap. Additionally, it is in the best interest of US companies to setup or help setup that kind of call/customer service center to help reduce cost to US-based customers.
I wish you good luck.