The emergence and relative maturity of web browsing enables a general understanding of delivered quality for this service. When browsing the web, users complain if the delivery of information is slow and if the connections to the service provider are busy. There is also the usual, general complaint that the service is too expensive for what it delivers. Many ISPs are learning the hard way what happens when they do not meet their users' service quality expectations. Factors such as transmission line performance, data delay, data loss, service availability and price all affect the user's perception of service quality.
Telephone networks provide quality voice service.
Likewise, some ISPs offer good-quality access to the services of the Internet. However, multimedia communications service providers are facing early problems in their migration to multiple service delivery. Many telephone companies are offering Internet services over existing copper lines and are facing network engineering problems, such as correctly planning for future link bandwidth requirements. In addition, the quality of VoIP is less than what the PSTN offers in some cases. The key to providing service quality lies in the successful integration of network technologies that provide both voice and data services.