How does VoIP work?

Telephone cable consist of telephone part and data part

Not all consumers are aware of the fact that the telephone cable actually consists of two parts. One of these parts has previously been used exclusively for data traffic. This is the part for which you pay ADSL charges for receiving your broadband connection. The other part can only be used for traditional telephony, and is reserved for traditional telephone companies. All companies wanting to provide calls by means of traditional technology must pay the traditional telephone companies to access those you wish to call. The telephone companies must in turn charge you for these costs in the form of call units.

Telio differs from traditional telephone companies in that we use new and modern technology that enables us to provide the same calls over the data line for which you are already paying (the technical term for this is IP communication based on SIP (Session Initiation Protocol). In its simplest form, the service itself can seem similar to that provided with a regular telephone, but IP communication based on SIP also allows for calls with significantly better sound quality than that obtained with regular telephones, video communication, calls in combination with instant messaging, etc. If you wish, you can also keep your existing telephone number for making calls over the regular telephone network.

Transferring telephone numbers and calls to/from the regular telecom network is carried out by Telio’s local telephone companies such as Telio Telecom AS for Norwegian customers, Tellio Aps for Danish customers, and Telio Netherlands Bv which operates through XMS and Optibel for Dutch customers.

Cost saving for the consumers

The money Telio saves by utilizing modern IP-technology is used to provide the consumers with a significantly cheaper and better service than is possible with traditional services. Although we are convinced that, in time, all communication between our customers will be conducted exclusively over broadband lines, many will still need to communicate over the regular telecom networks for some time to come. That is why, as part of our service, we buy large amounts of traffic in the old telecom network, which we provide at low or no cost to our customers. One important difference to be aware of is that with Telio, the service follows you – wherever you are. In other words, you can take your ‘home telephone’ with you when you travel. This is a major advantage, but it is important to remember that you should NOT use broadband telephones to call the emergency services if you have taken your equipment away from home. For Telio, you are ‘at home’, no matter where you are when connected to a broadband connection. This means that you will be connected to the emergency services centre closest to your home, even when you have taken your telephone to another location.

Telio's services are simple to use and install

The only thing you need to do is connect a regular analogue telephone – fixed or cordless – to an adapter, and connect the adapter to your broadband outlet. Telio will provide the adapter.

It’s as easy as connecting any regular telephone. If you wish to use a computer while your telephone is connected, you must first connect a router, or switch, to the broadband outlet, and then connect both the adapter and the computer to their respective ports on the router.

Technical description of IP communications

This section describes in more technical detail how broadband telephone communication works, and explains to you why IP-to-IP communication enables us to provide significantly cheaper communication for you the consumer.

Technically speaking, Telio via Telio SA, is an IP-to-IP communications facilitator which bases its signalling on a protocol known as Session Initiation Protocol (SIP). The way in which this services works has many features in common with MSN Messenger and Skype, but is better adapted for use by users who want to be able to use hardware other than a computer to communicate, for example so-called ATA boxes (Analogue Telephony Adapter), which convert the signals that are created when you speak into a telephone into IP traffic, or so-called IP telephones, which are in fact nothing more than small computers that resemble regular telephones.

If one compares this with a regular telephone service, the SIP address is equivalent to a person’s name, the IP address is equivalent to a person’s telephone number, and the SIP proxy functions as a telephone directory; in other words where a person (an SIP address) makes an enquiry if he wants to know the telephone number (the IP address) of another person (another SIP address).

It is the way in which the communication between two users is produced, and who plays which role in this production, which distinguishes IP-to-IP broadband telephony from regular telephony (and at some time in the future all broadband telephones will be IP-to-IP). The role of the service provider is more comparable to that of a supplier of content who facilitates communication rather than that of a traditional telephone company.

In fact, IP-to-IP (peer-to-peer) broadband telephony involves the use of a computer network, typically the internet, to communicate (both verbally and in combination with text and/or video) between two endpoints. See figure below.

A typical endpoint would be you, the subscriber, or the IP side of a media gateway that facilitates interconnection between the regular telecom network and the internet. Telio SA does not operate its own media gateways, but we have arranged it so that the SIP address you are assigned with us can also be registered with telephony service providers who operate such interconnection with the telecom networks.

Put simply, one can refer to the IP-to-IP communication we facilitate as an automised telephone catalogue, in the sense that our SIP proxy servers find and help to establish communication between two endpoints that each have their own IP address (you and the person you want to communicate with, whether it be another end user or the IP side of a media gateway belonging to a company who provides interconnection with the telecom network. And since the internet is a global network, these IP addresses, both yours, the one you are communicating with and the SIP proxy server, can be physically located anywhere in the world. These days, when one has access to broadband on aircraft too, you can even sit on an aircraft at 10,000 metres altitude and communicate via the IP address designated to you by the aircraft’s broadband line.

The role of a SIP proxy server is simply to make it as easy for two parties to communicate over the internet as over the regular telecom network. All you need to know is the telephone number or SIP address of the person you wish to contact, and the proxy server will keep track of which IP address the SIP address is on at any given time. Once contact is established, we have no further role to play in the call, and do not participate in the transmission of ‘voice packets’. The transmission of voice packets occurs directly between the devices themselves, over the broadband connections to which the endpoints subscribe through their broadband service provider.

In fact even if our SIP is removed, all telephone calls (in the world of IP technology these are usually referred to as 'communication sessions') that are already in progress are not affected whatsoever. Because the network transmitting the voice packets is the customer’s own broadband connection, the calls proceed as normal.