This page presents some frequently asked questions and answers
concerning the new telephone-domains.
Besides the information offered here, we have a list
of general questions
and answers about the domain system, which is worth reading
and well-suited to impart a solid basic understanding for this topic.
Example: The number of a mobile phone in Germany is to be registered. The
network operator may be Vodafone (code 172), and the number may be 123654.
For the registration, all numbers have to be written in reversed order
and the suffix ».9.4.e164.arpa« has to be added. In our example,
the domain »4.5.6.3.2.1.2.7.1.9.4.e164.arpa« would be registered.
ENUM serves for addressing purposes only. It has nothing to do with the
actual transmission of voice signals or the duration of calls, etc.
This is why ENUM does not deal with this topic at all.
The operating companies of telephone and data networks are already developing
pricing models. In most cases, both telefon partners a connected to the internet
anyway, so that their calls are not routed through external operating companies
of telephone.
So far, phone companies do not check whether the called phone number is an
ENUM-number (see Overview).
Therefore, the telephone has to provide some intelligence itself to process an
ENUM DNS inquiry.
Technically seen, an ENUM domain is just a normal domain
so that every device with an IP-number can be addressed.
What kind of services will finally communicate over these connections is up to
the fantasy of the users. Possible services are, for instance,
speech, e-mail, voice-mail-boxes, call forwarding, e-mail read aloud-systems, etc.
After all ENUM test runs have been done from the
DENIC
the choice in their favor was easy. The DENIC now provides the registry for
ENUM domains in germany.
This is one of the basic problems with ENUM domain registration.
There has to be a means to avoid that your neighbor, for example,
registers your phone number and then answers your calls.
For registrations we ask you to send us a copy of the last bill from your phone
company.
Next to the already known entries (e.g. A-, MX-, NS-entries) there
are the newly introduced Naming Authority Pointer (NAPTR)
Resource Records for ENUM (see below) .
ENUM is often reduced to speech communication. But it offers far more
than that as you might see when looking at the following overview of
questions that have to be answered when establishing a connection:
What kind of interactivity do I want to achieve?
I would like to send the addressee something to work on
(e-mail, voice-mail).
I would like to fetch information from the counterpart
(website, public-key).
I would like to establish a dialog with my opposite
(phone, chat).
What sort of material do I want to send my counterpart?
Text.
Text and pictures.
Speech.
Video.
What situation is my counterpart in?
At work.
At home.
Always available, no matter where (emergency stand-by).
Available only if the counterpart has time.
All those scenarios are possible with a single ENUM domain.
Naming Authority Pointer (NAPTR) Resource Records are a new way
for addressing the target. It is much more complex than
MX-records, for example, but it offers a multitude of possibilities.
It is even possible to use regular expressions for the assignment of services.
The following elements are included:
Element
Description
Example
Order
Determines the order in which this entry is listed.
1
Preference
Comparable to priority in MX-records. If more that one entry is
available, the one with the lower number is preferred.
20
Flags
Indicates how the following fields have to be interpreted.
At the moment only »U« is allowed.
It means that the following rule is the only one and that the result
of the rule will be a URI.
U
Service
Defines the service that is being addressed with the entry.
Bevor the service itself the prefix »E2U+« must be given
to indicate that a conversion from ENUM description
to target-URI has to be made.
"E2U+mailto"
Regexp
Regular expression that implements a substitution.
This makes it possible to unify different notations of an e-mail
address.
