tion with many of the benefits of a dedicated network, without the expense of deploying and maintaining equipment and Figure 10-5 Wireless The VPN. Remote W-ISP Internet Extranet Corporate HQ Firewall Main Site Corporate VPN Access Service Points Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. SGSN-to-GGSN (Gn) and GGSN-to-PDN (Gi) Interface Chapter 10 facilities. Often VPN solutions include the use of services from telecommu- nication carriers. The term Virtual Private Network originated with voice long-distance deregulation in 1984. In the last 10 years, data VPNs have also become popular and are often implemented using Frame Relay ser- vices. Within the past few years, VPN services based on the Internet have become available. With the expansion of IP into our networks, VPNs now span from voice to data services, from wireline to wireless. Operators offer value-added service via connectivity at far lower rates than dedicated leased lines. The GPRS VPN operator provides a range of services from full outsourcing of the corporate data network operation to providing selected parts of it, like remote access, site connectivity, or extranet services with partners. Access by remote mobile workers is becoming more important as telecommuting increases and their productivity gains become an obvious part of the information delivery process. GPRS wireless access services make this possible. Many GPRS operators will enter this lucrative and com- petitive market. Sometimes the computers we don't see will participate in VPNs: in vehicles, vending machines, and appliances that are remotely monitored where wireline connectivity is not feasible or financially practi- cal. W-VPNs will share resources in the GPRS backbone. GPRS VPNs are based on standard IPs and feature seamless interoperability between providers. Some providers may support multiple access tech