Asymmetric Digital Subscriber Line is one form of the Digital Subscriber Line technology, a data communications technology that enables data transmission over copper telephone lines. It achieves this by utilising frequencies that are not used by a voice telephone call. A splitter, or DSL filter, allows a single telephone connection to be used for both ADSL service and voice calls at the same time. ADSL can generally only be distributed over short distances (typically up to 2 miles) from the telephone exchange.

Fixed Line

the term used to describe traditional telephone connections, i.e. those that operate solely over telephone company wiring.

Geographic numbers (Global DID)

These are the typical numbers allocated to residential and business users by telephone companies. These numbers have a prefix (7 or 8 digits in Malaysia) which identify the region that the number is from.
e.g.: Kuala Lumpur: 03 (prefix) 20355888 (allocated number)


The term hardware refers to the physical equipment used to provide a given service. In the case of astervox Cloud Telephony, hardware typically refers to the telephone handsets provided by us.


IP – Internet Protocol (IP) is the principal communications protocol used for relaying information packets across a network. Responsible for routing packets across network boundaries, it is the primary protocol that establishes the Internet.


Public Switched Telephone Network, the public telephone network operated by various carriers around the world.


Session Initiation Protocol (SIP) is an Internet Engineering Task Force (IETF) standard protocol for initiating interactive user session for multimedia elements such as video, voice, chat, gaming, and virtual reality.

SIP Trunk

A Session Initiation Protocol (SIP) Trunk is a Voice over Internet Protocol (VoIP) service that connects a company’s private branch exchange (PBX) telephone system to the public switched telephone network (PSTN) via the Internet. Using a SIP trunk can simplify administration and reduce costs for the organisation as the SIP connection typically uses the same Internet access that is used for data. This often removes the need to install fixed line circuits such as Analog Lines or Primary Rate Interface (PRI) telephone circuits.

Voice Priority / QOS

Voice priority – the prioritisation of telephone audio traffic over a network connection, in order to maintain digital call quality. Also referred to as Quality of Service (or QoS).


ISDN (Integrated Digital Subscriber Line) is a digital telephone technology used to carry calls to predominantly business users. In Malaysia the use of PRI Lines (Primary Rate Interface) can support up to 30 ISDN channels over a single cable giving you the capacity to withstand 30 concurrent calls (calls at the same time). Primary Rate Interface (PRI) come with high cost of installation and long term contracts but provide the highest call quality.


Private Branch Exchange, a term used to describe private telephone systems.


Power over Ethernet is a technology used to power devices over their Ethernet cable, removing the need for separate power supplies.

Leased Line

A leased line is a dedicated symmetric connection between two or more locations. It is also known as a ‘Private Circuit’ or ‘Data Line’.

Cloud Telephony

A fully managed and hosted telephony service run on a core platform by a service provider for both businesses and residential user. Users are connected via the Internet to the providers platform and all calls are transported over the Internet. Additional features such as voicemail, call routing and call forwarding are available either as standard or for additional monthly fees.


A softphone is a software program for making and receiving telephone calls over the Internet using a general purpose computer, rather than using dedicated hardware. Often a softphone is designed to behave like a traditional telephone, sometimes appearing as an image of a phone, with a display panel and buttons with which the user can interact. A softphone is usually used with a headset connected to the sound card of the PC, or with a USB phone.

Traditional telephone systems

the term refers to telephone systems which communicate using PSTN lines, which offer less flexibility than modern VoIP systems.

Unified Communications

Unified communications (UC) is the integration of real-time communication services such as instant messaging (chat), presence information, telephony (including IP telephony), video conferencing, data sharing, call control and speech recognition with non-real-time communication services such as unified messaging (integrated voicemail, e-mail, SMS and fax). UC is not a single product, but a set of products that provides a consistent unified user interface and user experience across multiple devices and media types.


Voice over Internet Protocol is a technology that enables telephone calls to be made over computer networks like the Internet. VoIP converts analogue voice signals into digital data packets and supports real-time, two-way transmission of conversations using Internet Protocol (IP).