Circuit switching is a method of communication where a dedicated circuit or channel is established for the duration of a communication connection to transmit data between endpoints. Integrated Services Digital Network (ISDN) is a digital line network that can be used for circuit switched or packet data communications. Transmission Control Protocol/Internet Protocol (TCP/IP) is a protocol often used for reliable data transfer when transmission speeds are slower than other protocols. A dial-up connection establishes communication between a personal computer and an Internet service provider by dialing the provider's telephone number to connect over telephone lines.