👉 isdn is an abbreviation for "internet service provider." It stands for Internet Service Provider, which refers to a company that provides internet access services over a network. These providers include local phone companies and other organizations that offer internet access on their networks. Isdn services can be provided by private companies or public entities such as government agencies or businesses. They provide internet access through the use of fiber optic cables, dial-up modem technology, or other forms of wireless technology.