conversation

A peer-to-peer instant messaging session between two (only) participants.

conference

A multiparty SIP-signaling conversation that is centrally controlled by a conferencing server. An instant message session with more than two participants is usually a conference.

endpoint

The origin or destination of a data or voice transmission, typically a telephone or a VoIP or IM client.

enhanced presence

Presence with added capabilities to provide custom information and additional details about a users status. This information can be presented differently to different users, depending on what the subject of the information allows.

Enterprise Voice

The Microsoft software-powered VoIP solution that includes connectivity with PSTN gateways and interoperation with PBX installations.

external user

A user who signs in to Communicator Web Access from outside the organizations firewall, typically over the Internet. An external user can be signing in from such locations as home, a customer work site, or a public Internet kiosk in an airport or an Internet cafe. Also called "remote user."

HTTPS

Secure Hypertext Transfer Protocol (HTTPS) is HTTP over TLS, whereas HTTP is HTTP over TCP.

instant messaging (IM)

Sending and receiving text messages in real time over the Internet or an intranet.

internal user

A user who signs in to Communicator Web Access from within the organization's firewall.

ISA Server

Microsoft Internet Security and Acceleration (ISA) Server 2006, a server that functions in Office Communications Server deployments as a reverse proxy.

PSTN

Public switched telephone network, the traditional landline network for telephones.

PBX

Private branch exchange, a system for managing and routing calls. A PBX can be a conventional phone network, a VoIP-based network, or a combination of the two.

Presence

The ability to detect and display information about whether a user is online or not and, if online, about the users current activity.

SSO

Single sign-on. A system of authentication in which a user who has signed in to one service can sign in to additional services without providing credentials each time.

TLS

Transport Layer Security [v1.2], an open security protocol that is designed to provide privacy and data integrity between two communicating applications.

unified communications

A systems-based approach to unifying telephony, instant messaging, presence, and Web conferencing.

VoIP

Voice over Internet Protocol, an open protocol for transmitting voice data as packets over the Internet or an intranet.