Although few office environments and even fewer homes use a pure VoIP infrastructure, telecommunications providers routinely use IP telephony, often over a dedicated IP network, to connect switching stations, converting voice signals to IP packets and back. The result is a data-abstracted digital network which the provider can easily upgrade and use for multiple purposes. Corporate customer telephone support often use IP telephony exclusively to take advantage of the data abstraction. The benefit of using this technology is the need for only one class of circuit connection and better bandwidth use. IP telephony is commonly used to route traffic starting and ending at conventional PSTN (Public Switched Telephone Network) telephones. VoIP is widely deployed by carriers, especially for international telephone calls. Electronic Numbering (Enum) uses standard phone numbers (E.164), but allows connections entirely over the Internet. If the other party uses Enum, the only expense is the Internet connection. Companies can acquire their own gateways, eliminating third-party costs — worthwhile in some situations.