es with whom the company deals, or even to the home of key employees. Two factors are impacting the use of private circuits (Wright, 1992): 4. To provide an overflow to the private network in times of heavy 1. Users are demanding high bandwidth at random times due to increasing use of services such as teleconferencing and high Security within virtual private networks is usually provided by use speed inter-network traffic. of encryption techniques. 11/16 The telecommunications industry Virtual private networks are often associated with the concept of outsourcing, although they are quite different. In outsourcing (Kir- Owner: Customer Owner: Customer or third party User: Customer User: Customer van, 1992) a separate company provides an agreed level of service Operations: Customer Operations: Third party to the customers, relating to the operation of their communications network. This company may be the original supplier of the telecom- Private Outsourced munication facilities or it could be a third party. The company may Network Network also provide virtual private networks. Outsourcing may be con- sidered to be the equivalent of Facilities Management (FM) as used in the IT industry. There are several advantages to the customer in outsourcing: Virtual Private Network 1. The customers can concentrate on managing their core business and leave the management of their telecommunications net- Owner: Supplier work to the outsourcing company. Users: Several organisations 2. Often the capital cost of transmission equipment required for Operations: Supplier the private network can be rolled into the running costs of the network, so the customer does not need to meet a large up-front bill. Figure 11.12 The relationship between a private network, an outsourced network and a VPN 3. The outsourcing company usually has a large pool of skilled resources it can draw on in solving network problems, if they arise. Other examples of CSTA are the use of different numbers which provide various recorded messages to the callers; the use 