1820 is a Swiss telephone directory and information service operated by AP Dialog AG. It helps callers find telephone numbers, addresses and opening hours throughout Switzerland, with an information team available around the clock. Customers can request immediate connection to the number they are seeking, avoiding the need to write down details and dial again. The service is accessed by calling 1820, at the listed rate of CHF 1.99 per call and per minute.

Beyond telephone enquiries, 1820 offers a wake-up call service and 1820 Concierge. The concierge provides information and personal assistance with everyday questions and requests. For business customers, the company also supplies Swiss directory data, and its website references a business directory. 1820 additionally offers the option to connect AI assistants such as Claude or ChatGPT through an MCP server. The service is presented in German, French, Italian and English, serving individual callers and organisations seeking practical information or directory-related services.