but, as telecommunication advances, tariff structures become increasingly more complex. Usually there is the option of calling collect (in the UK known as reversing charges), where responsibility for charges normally paid by the caller is accepted by the recipient. Tariffs also depend on the bandwidth provided. For example, dial-up modem connections are charged at normal telephone costs, but connections such as DSL are usually charged using a completely different accounting system due to their always on nature. Special tariffs Increasingly, in some countries, the call charges are fixed at a monthly rate and included as a supplement to the standing charges, known as inclusive calls. Emergency calls can invariably be made without charge. Most countries have a number sequence that enable the caller to make calls without charge, sometimes known as free calls or freephone, these are usually used by companies for their sales line (in the UK these are 0800 and 0808 numbers and in the US they are 800, 888, 877, 866, 855 and 844). Tariffs substantially in excess of the normal rate, known as premium rate, are used for information services, competition entries and pornography calls. These telecommunications tariffs originated with the advent of public phone service. In these times, the services provided were less complex, and customers were able to simply read the tariffs to understand how much they would be charged for each type of call. Additionally, only a few telecommunication industries participated in the market, facilitating decision-making. As the market became increasingly competitive, the need for regulation decreased. In 2001, the U.S. Federal Communications Commission (FCC) declared the telecommunications market was fully competitive in the United States, and eliminated the need to file tariffs with federal regulatory agencies. However, to continue operating, many state and local governments still require telecommunications tariffs. Impact of tariffs on traffic Call minutes are highly elastic against price, this means that the demand for call minutes varies greatly according to price. A slight decrease in price leads to a great increase in call minutes. The higher the price, the more this effect is noticeable, for both business and residential customers on international or local calls. This means that it is often the case that more revenue is achievable at lower prices, that is, E < -1. Internet traffic research show that the traffic intensity is directly affected by the tariffs charged in connecting customers to their Internet Service Provider