What Is VoIP? How About PBX? ITSP?? - Confusing Telephony Acronyms Made Simple

“What is VoIP?” is one of the questions we most frequently get here at Intouch Communications. In fact, when it comes to acronyms it is by far the most common enquiry we get from customers both old and new. This has become more frequent as time has gone on, clear evidence that hosted VoIP is taking off in a big way when it comes to business telecommunications. All industries have their own set of baffling acronyms to decipher and telecoms is no exception. Listed below are the top acronyms people enquire about - read on to find out what VoIP stands for as well as how it relates to ITSP and PSTN.


What Is VoIP?

VoIP stands for Voice over Internet Protocol. It sounds very technical but all it is describing is the technology used to transmit voice services/calls through the internet, including wirelessly through local WIFI or mobile internet. VoIP allows internet phone calls to be made without the need or installation of traditional phone lines. This upgraded service allows for more features and greater functionality than a traditional phone service.

What Is SIP?

Many people who use these services daily, including those working in the telecommunications industry don’t know what SIP stands for. It can be quite a complex subject and its uses are varied. SIP stands for Session Initiation Protocol and for our purposes here today can be thought of as a kind of language that VoIP devices use to communicate. SIP is how these devices send and receive information to understand each other.

What Is ITSP?

ITSP stands for Internet Telephony Service Provider. An ITSP provides access to the equipment and services associated with VoIP telephony. Also know as VoIP service providers, their main role is to facilitate internet phone calls easily and seamlessly into businesses and organisations telecommunications.

What Is PBX?

PBX stands for Private Branch eXchange. These can vary in size and complexity but basically these are telephone systems which can comprise both hardware and software and are used in a business or organisation to manage incoming and outgoing calls as well as calls within the organisation itself.

What Is PSTN?

PSTN stands for Public Switched Telephone Network. This is the vast infrastructure of all of the world's circuit switched telephone networks. This interconnection of every country's public telephone networks allows callers from all over the world and from all kinds of devices to communicate with each other, allowing landline calls, VoIP calls and mobile/cellular calls to connect with one another.

Hopefully this has been a helpful primer on some of the more popular acronyms that telecommunication service providers and operatives use. Next time you overhear a colleague mention they need to look into a system capable of making internet phone calls, you can simply tell them to speak to a reputable ITSP and explain to them what VoIP stands for.


We pride ourselves on delivering the highest quality customer service experience. If you have any questions regarding acronyms or if we can help you in any other way, don’t hesitate to fill out our enquiry form or call us on 01252 241000 today!

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