| Proceedings | Social Programme | List of Participants | Practical Information | Speakers | Exhibition |
ENUM and its implication for directory
publishing
Robert Schischka, Enum.at
I will begin my presentation with a short introduction of ENUM. ENUM enables users to find each other in the VoIP market. This crucial service will be an important part of the telephony infrastructure. I will introduce the technical aspects for ENUM and discuss their implications. We are the first company running this as a commercial service. It is a new technology. We are at the beginning of development. We will see new and different applications emerging in the near future. The examples I give will serve to illustrate the technology and are not a complete enumeration of all the possibilities. I will then address the impact in the directories publishing market.
a. Enum.at Background
Enum.at was founded to run the operational, technical and administrative framework of ENUM with the Austrian country code 43. It is a service related to the telephony numbers and its administrative structure strictly follows the country codes. The Austrian code 43 has been given to us to handle by the Austrian regulator. This is different to the classic Internet business where things have evolved more informally. The integrity of the number range is very important for a regulator. It is important that we have a strict policy about who is able to claim ENUM domain for an existing telephone number. The regulatory framework is designed by the regulator. We have an official contract with them to run the technical and administrative services in this critical infrastructure.
Our service began in December 2004. Austria was the first country to start ENUM services. We ran a trial for about two years and then began a real production service. Many other countries in Europe, such as Germany, Switzerland and Sweden, are involved in trials. Worldwide, 43 to 45 countries are running trials for different kinds of ENUM services. Five or six of these have moved into a production phase. The differences between trial and production lies not so much in the technical aspects but in the regulatory and legal aspects. Who is authorised to give a certain ENUM domain to a certain telephone number? What are the commercial terms and conditions? ENUM is based on proven technology. It is a different application of the domain name system that has been running for about 25 years all over the world. The technical foundation has thus been laid and is based on International Engineering Taskforce (IETF) international standards. This is not something that a weird company in Austria has invented. Everyone is free to implement the standards.
We are the registry for the country code .at. Every domain name registered in Austria is registered in our database and run by our name service. ENUM applies this kind of technology to telephony numbers. We run a distributed, high‑availability database. Our service runs seven days a week and 24 hours a day on a large scale. We have shown that we can run such a service for several years without any major incidents.
b. What is ENUM?
ENUM is a way to make your phone number usable for addressing users on the Internet. Importantly, ENUM makes this information publicly available for queries. Everything entered in the ENUM database can be seen by every Internet user in the world. You are not able to hide certain information. ENUM should be as open as possible. It is designed to be queried by mobile phones, VoIP phones, routers, and so on. It is part of an infrastructure. Every entry in the database can be retrieved in an open way.
ENUM is an application of the DNS of the domain name system. Information is retrieved in the database by the telephone number. The telephone is in the international format e.164 designed by the International Telecommunication Union (ITU) as part of the International Numbering Plan. Every official number used worldwide can be used as a key for this type of database.
ENUM adheres to international standards and is implemented by existing software. Existing software is configured in the appropriate way and offers the same reliability and scalability of the Internet.
ENUM is a generic service. It is not limited by VoIP technology. It is about IP‑based communication in general. For example, my postal addressing, my web page and so on can be retrieved by every client who keys in my telephone number.
Requests For Comments (RFCs) are the by‑laws of the Internet and the technical standards defining how inter‑operable services are designed. RFC 3761 says that everyone is free to use the standard to implement services.
To insert the ENUM in the database, DNS requires you to reverse the number and put dots between each digit. This is done by software. This is a simple technical trick that will not affect the end user.
c. Using ENUM
One of the more easily comprehensible applications of ENUM is that which allows two parties on the network to find each other if they only know the telephone number and nothing else. In this scenario – ENUM‑enabled VoIP – both parties are connected to PSTN and to the Internet. Neither knows if the other can be reachable on VoIP. They may be using different carriers. The caller enters the telephone number into the database. This number is associated with an Internet telephone number. Be aware that telephone numbers in the VoIP system look a little different from those in the traditional PSTN. The VoIP numbers look more like email addresses. The caller then dials this number, makes an ENUM hook up in the database, queries whether there is any kind of contact information associated with the number. He receives the additional information. In this scenario, the other party can be reached by an Internet protocol, SIP. The address of the user is then given. The caller can decide whether to use PSTN or the Internet. We can assume that the Internet is the cheaper. He can thus use the information to connect on the Internet with the other party.
You can do this without ENUM. However, in this case, one of the parties would have to communicate the fact that he is reachable on the Internet and give his email address. One of the core benefits of the ENUM system is that you do not have to tell everybody that you are reachable but just make an ENUM entry. Thus, everyone who makes an ENUM query gets your contact information.
Using ENUM, companies with different branch offices around a country or internationally can get a very quick return on investment. They just have to add a small box to their Private Branch eXchange (PBX) telephony system. It is very easy to roll this out to different branches and to coordinate it. Once this is done, you publish the information that you can be reached using the Internet. You will then be found. There is no need to make big project schedules or to ensure that everyone knows your new address. Boxes cost between €500 and €2,000, depending on how many lines you want to handle. Anyone who makes an ENUM query will find you.
d. The ENUM database
ENUM domains are created for existing telephone numbers. The rule of thumb is that you have to have the right to use the telephone number to use the ENUM domain. You request the ENUM domain corresponding to your existing number from an Internet Telephoning Service Provider (ITSP). There are no new numbers generated by ENUM. The process of proving that you are entitled to use a certain telephone number is important. As a registry is a centralised database, it may be a perfect source for generating directory entries. For example, we hold all the user data for all ENUM‑enabled Austrian numbers. It would thus be easy to make a directory of users.
The ENUM database does not hold any information other than contact details. However, within ENUM, you find a link to other locations, such as a web page, where further information, such as current availability, can be retrieved. For example, the result of a query to a telephone number could be a virtual business card delivered to the calling party.
Directory assistant operators could use ENUM to offer additional information to the customer. For instance, from the telephone number you can retrieve the postal address, ENUM or web page, all information that can be given to the customer. Conversely, when caller ID identifies a number, you can make queries on the calling party. You can get the mailing address of the caller, for example. You can then send the caller the information you find via email, in a PDA or as a virtual business card.
e. Disadvantages
One of the downsides is that ITSP customers have a different mindset to telephony carriers. They do not like to publish too much information about their customers. Their customers have learned that too much directory information means spam. Many VoIP service providers are using an opt‑in strategy for directories. Therefore, new VoIP customers may not publish their directory information.
ENUM associated Internet addresses with phone numbers. Today’s major application is VoIP call routing. Keep in mind that this is just one application. One of the benefits of open protocols like SIP and ENUM is that it is easy to develop new applications. It is not like in the TDM world where you have to spend millions of dollars, buy expensive machines and hire specialised engineers. It is easy to set up new applications, which could bring a new dynamic into the market. I am sure we will see some exciting new applications in the future. If Nokia decides that it likes one of these new applications and distributes it on its handheld devices, there will be millions of new customers. The idea of contacting people using a telephone number is not a new one but it is simple. ENUM as may be useful in enriching directory information and as white page data. However the mindset is a little different here.