The Internet Locator Service (ILS) Protocol is an extension to the Lightweight Directory Access Protocol (LDAP). This protocol uses LDAP-style requests to store and retrieve information in an Internet Locator Service (ILS) dynamic instance store, such as people or conferences. It is used for communication between collaboration clients using the Telephony Application Programming Interface (TAPI) and an ILS Server. The ILS is a dynamic directory service, primarily used to enable a client to find another user's network presence (usually this means the user's IP address) while online. Similar to how a person's telephone number is located in a telephone directory, a person's network presence can be contained in a computer directory such as ILS. The primary difference is that telephone numbers do not change very often, while a user's IP address often changes every time a user connects to the Internet/network. ILS can store information related to peer-to-peer and conference or multicast events.
ILS is used by two Windows-based clients: Microsoft NetMeeting 3.01 and TAPI Dialer 1.00. TAIL was accessible via the Internet Locator Service API library supplied as part of the NetMeeting 3.01 software development kit (SDK).
Sections 1.8, 2, and 3 of this specification are normative and can contain the terms MAY, SHOULD, MUST, MUST NOT, and SHOULD NOT as defined in RFC 2119. Sections 1.5 and 1.9 are also normative but cannot contain those terms. All other sections and examples in this specification are informative.