In this scenario, users dial into a service provider's point of presence, establish a tunnel back to headquarters over that provider's network or the Internet, and authenticate themselves to gain access to the corporate network. There are many reasons to use a VPN for remote access. First, there is the cost savings on the calls. The cost savings can be substantial. Significant cost savings can even be realized when using hourly rate premium ISP services.
Further savings can come from reducing operational costs associated with supporting remote users.
For example, when using a VPN, companies can get rid of their modem pools and remote-access servers. Additionally, companies may be able to save other communications charges. A complete changeover to a VPN would eliminate the need for the T1 line for dial access. The traffic from these users would be rolled over onto the existing Internet access line. Thus the monthly cost of a T1 line to support dial access would be eliminated.