SipExchange Terminology

The following table explains some of the terms used in the SipExchange documentation throughout this site.

Advanced intelligent network (AIN) Most modern telephone switches (also called the Service Switching Point or SSP) support the concept of an “external call control” mechanism. While handling a call between two parties, on certain pre-configured points (called trigger points) in the call, it can send a query to an external Service Control Point (SCP) asking the SCP how the call should be handled. The SCP sends a response specifying how the call is to be handled. The responses may include (a) terminate the call, (2) route the call to another user, (3) continue processing the call. This mechanism is called the Advanced intelligent network or AIN. AIN enables SCPs to provide external call control and enables new features to be developed outside of the SSP. For example, if during call setup, the party being called is not available, the SSP is configured to send a query to the SCP at this point of the call, and the SCP sends a response forwarding the call to a voice mail device, the voice mail feature is implemented without having to make any software changes to the SSP. The idea is that the SSPs are typically legacy systems that are difficult to add features to and SCPs are computers systems where such service logic can be created more easily.There are standards that have been defined by various telecommunications bodies that specify the trigger conditions, communication protocols between the SSP and SCP and even how the service logic can be created. These standards allow SSPs and SCPs from different vendors to talk to each other. However, in reality, many vendors have their own extensions to the standards, and SCPs and SSPs do not always work together seamlessly.
Call detail record (CDR) Call detail records are information about a call that was made or received by a switching system. It contains all the information about the call including calling and called addresses, call duration, etc. The CDRs are stored in the switch database and are later retrieved by billing applications for creating customer invoices, etc.
Calling address The calling address refers to the SIP address of the user initiating a call.
Called address The called address refers to the SIP address of the user receiving a call.
Domain In the IP network, each computer has an IP address and in many cases, the IP address maps to a name – called the domain name. Examples of domain name include “” or “”. For the SIP networks, the same concept is used and each SIP user has a SIP URL that consists of an user name and a domain similar to an email. An example of a SIP URL is where “amit” is the user name and “” is the domain name. When you set up the SipExchange server, it allows you to manage more than one SIP domain. For example, from the administration user interface, you can create domains “” and “” and assign subscribers (or users) to each of the domains. That way, your SIP service can serve more than one domain. Note that if you deploy the application in a real IP network, the domain names must resolve to the IP address of your SipExchange server.
Feature Feature refers to subscriber features like “call forwarding”, “call waiting”, “voice mail”, etc. When you subscribe to a telephone service, you can select from a list of features that the service provider offers. There are features that you do not see as a subscriber. These features apply to the entire switch or to a domain. For example, the toll free feature in a switch allows a switch to translate toll-free numbers into real telephone numbers by looking up the dialed digits in an external database. The SipExchange application is a switch that comes with many in-built features and enables features developed by other vendors to be “plugged in” using the AIN/IN mechanism.
Intelligent network (IN) Same as AIN. These terms are used interchangeably.
Payload Payload refers to the voice, video or other multi-media packets that are exchanged between telephones to transmit voice/video and other multi-media data. When an user speaks on a phone, the telephone digitizes the voice into packets and transmits the packets to the other end. The majority of messages exchanged between the telephones are payload data because voice, video or other types of payload tend to take up a lot of bandwidth. An important requirement is that the payload be delivered in real-time, as interactive conversations between two parties require a party to hear the other speak in real-time.
Portal A portal is a web site from where an user can all the information and services provided by a service provider. Typically, a portal is very flexible. The users can modify the look and feel of the portal and arrange stuff in a way he/she wants. The service provider can easily add new content and applications into the portal.
Service control point (SCP) Please read the terminology section on AIN.
Service switching point (SSP) Please read the terminology section on AIN.
Signaling Signaling refers to the messages exchanged between telephone and switches or between switches to set up and tear-down calls. It also refers to messages exchanged for call control purposes. The traditional signaling protocols include SS7, ISDN, etc. SIP is a popular protocol for signaling used for voice over IP (VOIP) calls. Another signalling protocol used for VOIP is H.323.
Soft phones Soft phones are computer software that can be installed on your desktop, your PDA or your mobile phone that allows you to make phone calls. Basically, you can use your desktop, PDA or mobile device connected to the Internet as a phone. Examples of such phones include Microsoft Messanger, Skype, Yahoo, etc. Some of these phones use standard communications protocols like SIP. Others use proprietary communications protocols.
Subscriber A subscriber is a user of a service. When you buy a telephone service from a service provider like Vonage or British Telecom, these companies refer to you as a subscriber.
Trigger Please read the terminology section on AIN.
Voice over IP (VoIP) Initially, the Internet was envisioned to provide data services like email and the world wide web. Then came the idea that we can also use the Internet network for setting up voice and video sessions. In other words, we can use the Internet for making phone calls for free! For this to work, communicatons standards must be defined so that phones and servers from different vendors can still understand each other. There are a number of competing standards for VoIP communications. H.323 and SIP are some of the most popular ones. In recent years, SIP has emerged as a protocol of choice.
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