The BPO sector is a very tricky place to be in, the contract can be reviewed anytime ie upwards, downwards or even thrown out intoto.
When Airtel goes into outsourcing, trust they will outsource to indian firms and as such you can figure out what the employees will be going through. You can also bet that, while Airtel makes profits the outsourced company also makes profits but you can be sure the employees will go through hell of sorts.

just a thought