Advantages of VPN is :

VPNs promise two main advantages over competing approaches — cost savings, and scalability (that is really just a different form of cost savings).
The Low Cost of a VPN

One way a VPN lowers costs is by eliminating the need for expensive long-distance leased lines. With VPNs, an organization needs only a relatively short dedicated connection to the service provider. This connection could be a local leased line (much less expensive than a long-distance one), or it could be a local broadband connection such as DSL service.

Another way VPNs reduce costs is by lessening the need for long-distance telephone charges for remote access. Recall that to provide remote access service, VPN clients need only call into the nearest service provider’s access point. In some cases this may require a long distance call, but in many cases a local call will suffice.

A third, more subtle way that VPNs may lower costs is through offloading of the support burden. With VPNs, the service provider rather than the organization must support dial-up access for example. Service providers can in theory charge much less for their support than it costs a company internally because the public provider’s cost is shared amongst potentially thousands of customers.