Save Money
Cost-saving is the biggest benefit of outsourcing, followed closely by time-saving (which in itself is cost-saving, for time = money).

On average you can get someone answering your calls for less than half of what you would pay in the west. You save time in not having to recruit or train agents and if you do end up building a team of outsourced agents, you only have to deal with the one person, rather than all of them individually.
If you run a 24-hour office, then monitoring staff at all times, especially those on the graveyard shift is both difficult and time (cost) consuming. By outsourcing, you have staff working for you that are monitored 24 hours a day, 7 days a week. If you require a large team of agents/operators then you need to consider the office space to cater for them. By outsourcing you eliminate that extra cost completely, if your team grows, your overheads will remain the same.
With the money saved, if you are able to reinvest it back into your business, it gives you the opportunity to further grow your business. We always advice our clients to use that money for advertising, the more you advertise, the more work you get and so on.