Business VoIP
Jargon Buster
All technologies are fond of their specific jargon and the telephony/VoIP world is no exception.
In this page, we explain some of the most common terms you will come across if you are not familiar with the telephony/VoIP world.
Asterisk is the world's leading open source PBXi, telephony engine, and telephony applications toolkit. Offering flexibility unheard of in the world of proprietary communications, Asterisk empowers developers and integrators to create advanced communication solutions...for free. Being open-source means that there is no charge for the software, though for business use, the support, software updates, full regression testing and other features of a commercial software package are required. Digium is the company which maintains Asterisk and provides a Business edition of the software which we use today.
Within the VoIP world, calls may be switched between VoIP phones. In this case, the transmission of the call is exclusively by the Internet. There will be many occasions when a VoIP user wishes to call a user of the PSTN. To achieve this, the call must break out from the VoIP world and be switched into the PSTN world. This term is used to describe such calls.
A network device used to provide access between different types of networks. For example, a gateway may provide access into an external network such as the PSTN, the Internet or a private WAN.
Hunt groups allow you to group staff together into notional groups, such as accounts, customer service, sales desk and so on. Callers are directed to the group as a whole, not to individuals within it. You may choose to publish a separate telephone number for the group or you may get your receptionist to put callers through to it. Systems come with configuring options so you can decide how to manage calls to your groups, such as ring the phones in turn or ring all the phones. If all the members of the group are busy or unavailable when a call comes in, a voice messaging service takes a message for the group as a whole, or it can be diverted to an alternative extension.
In addition, time-of-day rules allow you to specify the periods when a particular extension is included in a hunt group. You may choose to use this facility if you share incoming calls across different groups of people, maybe part-time workers or if you wish to route calls to an emergency out-of-hours person when the office is closed.
You can also play a message to callers who have been routed to the hunt group. Perhaps you wish to tell them that you are aware of a particular service problem which you are working on. Such a message might be sufficient information that the caller no longer needs to speak to a person.
Of course, each individual member of the hunt group also has an extension number so anyone may call that particular extension to speak to a specific person.
Integrated Services Digital Network. A group of digital transport services that use the circuit-switched PSTN. These came into operation prior to the general acceptance of the TCP/IP protocols used by the Internet but still remain today as an alternative to analogue services. ISDN transports are capable of integrating data, voice and video applications but run slower than other transports available today.
Many current-day PBXs connect to their serving telephone exchange using ISDN rather than individual analogue lines. ISDN is faster than analogue and it achieves a higher bandwidth on a copper pair than its analogue equivalent. VoIP-enabled PBXs may be configured to use existing ISDN lines as an intermediate step before changing to TCP/IP.
Phone menus are also known as IVR (interactive Voice Response) and will be well known if you phone call centres. An automated voice guides you through a menu of possible choices. Up until now, these features were only available on high-end telecoms systems, but now you can have this feature even on entry-level systems.
When callers phone in, they are presented with a company greeting and then given options such as “please press 1 for sales, press 2 for customer services, press 3 for accounts or hold for an operator”. You decide what the greeting and the options are and you record the messages yourself. The flexible configuration options of the systems allows you to direct the call to the appropriate extension or hunt group depending on the selection the caller has made.
“Hidden” menu options (ie options which are not advertised to the caller in the greeting) allow your staff in the field to select internal departments, hunt groups or conference rooms.
Digital data is wrapped up for transmission in packets. A packet can best be visualised as the electronic version of an envelope for transmitting data. Each packet is addressed with its destination which is used to route the packet through the various switching nodes of the Internet.
The data content of the packet has no significance to the Internet which is switching it; the semantic significance of the data is only understood by the sender and receiver. The data may be audio, video, text or speech; it might be part of a telephone call, a file download, an image or many other things. See also QoS.
PBX - Private Branch Exchange; PABX - Private Automatic Branch Exchange. These terms are hangovers from the "old days" of telephony given to subsystems which were used to mechanically switch internal calls within an organisation. PBXs were generally manually operated, whilst PABXs introduced automation. Nowadays the generic term PBX is used to describe any privately owned facility to switch calls, independent of the national network. Current systems are all automatic and software controlled.
Public Switched Telephone Network, sometimes also known as POTS (Plain old telephone system). The traditional telephone system provided by BT to switch calls between analogue phones.
A PSTN gateway is software/hardware configuration which runs either on your own platform or on a hosted platform to interface between the packet-switched digital VoIP world and the circuit-switched analogue PSTN world. It allows VoIP users to connect to users of the PSTN.
QoS
Quality of Service. The transmission of a speech data packet through the Internet needs to be fast if the quality of the sound is to be maintained. Unlike, say, a file download, where a delay of a few seconds is acceptable, this is not so for speech, where a delay of just a few milliseconds is detectable to the listener. Because the Internet is switching millions of packets all with different content, a QoS marker is attached to each packet to indicate its priority. Packets containing speech are given the highest priority through the Internet.
Session Initiation protocol. An interoperable protocol in the TCP/IP family of protocols. SIP is used to set up a call between two VoIP phones, locating them within the IP network and then handing over the call to the switches which will route the data packets.
Skype is proprietary software which allows users to make phone calls across the Internet. It is a closed system which is not interoperable with any others, such as standard VoIP. The main difference between Skype and standard VoIP clients is that Skype operates on a peer-to-peer model rather than the more usual client-server model. Skype usage requires a platform (such as a PC) on which to run the software for the duration of the call. Because of its peer-to-peer nature and its proprietary implementation, it is really only suitable for personal/domestic use. It is not targeted at the business user.
Telephony Service Provider. Like an ISP (Internet Service Provider) of the Internet, a TSP is the Internet access point for a VoIP user. A TSP is also responsible for managing calls to and from the PSTN (PSTN breakout calls) using a PSTN gateway.
Voicemail is the facility to leave a message for someone when they don't answer a call. In VoIP systems it replaces the personal answering machine. The Voicemail service is provided by the platform on which the VoIP system runs (either your own or a hosted provider) and as such is able to offer many features not available from a dedicated personal answering machine. Typical of these features is the ability to access messages from anywhere and to have those messages sent to you by email as an audio attachment.