# A - Link **Explanation of SS7 A - Link** SS7 (Signaling System No. 7) is a set of telephony signaling protocols used to set up and tear down telephone calls, route SMS messages, and perform other telephony-related functions. The 'A-Link' in SS7 architecture specifically refers to the Access Link which connects a Signaling Point (SP) to a Signaling Transfer Point (STP). An 'A-Link' is typically characterized by: * High availability and reliability. * Redundancy to prevent single points of failure. * Use in both national and international signaling. A typical SS7 network configuration ensures that the A-Link is robust to support critical communication signaling tasks. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://ss7.learn-telecom.com/link-types/a-link.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.