Gives you the freedom to get additional people when you need them without the commitment of taking them as your permanent employees.
Companies are given the opportunity to focus on core competencies, instead of alloting a large part of their resources to multiple back-end departments such as customer support, data entry, among others.
Gives you the time to focus on more important aspects of your business, without driving you to the edge with the unnecessary expenses.
Ideally, your business will have its own supervisors or managers and on-site management. When you outsource, you no longer need those positions because vendor will have its own supervisions and off-site management.