Thursday, May 19, 2005

FAQs related to the ENUM-enabled number range +43780

Richard Stastny VoIP and ENUM


Since I got many questions asked regarding the new number range +43780 that went into operation in Austria yesterday - even from ENUM Experts, I would like to answer the most important questions here.

What is difference of +43780 to any other number range?

The number range +43780 is linked 1:1 with ENUM. If we leave out for a moment service numbers (e.g. 0800 freephone numbers), any other E.164 number range is first assigned in blocks to a network operator. The network operator in turn assigns a number out of this range to the end-user. The block assignment is necessary to allow other network operators to route calls to these range of numbers to the proper destination network via the so-called Point-of-Interconnect. If number portability is introduced, an IN-query may be necessary to route the call to the PoI of the network of the new operator.

An end-user may only opt-in with a given number in ENUM if he has the right to use this number (the number is assigned to him by an operator or directly by the regulator) and he is proving this fact to the ENUM Registrar. This is called Validation.

With the number range +43780 the opposite is the case. The number is first delegated in ENUM like any other domain name, and is assigned afterwards to the domain name holder (for political correctness). Therefore the complicated and expensive validation process is not necessary.

How are +43780 numbers routed on the Internet?

Like any other numbers in ENUM, directly on the Internet from calling to called party.

How are +43780 numbers routed on the PSTN?

All other E164 numbers are routed on the PSTN regardless of ENUM, in most cases to the still existing end-point on the PSTN. +43780 numbers are always routed to the nearest ENUM-enabled gateway. This gateway is querying ENUM and routing the call like any other ENUM-enabled server or client according the information contained in the NAPTR records.

Where is the nearest ENUM-enabled gateway?

Ideally within the originating network. If the originating network has no gateway, it should route the call to a the nearest network operating a gateway. This may be in the same country or in different country. In the worst case the call is routed via the international network to Austria.
This guaranties that a call to +43780 can be completed from any network in the world by default.

What are the tariffs to +43780 numbers?

The tariffs are charged to the end-user by the originating network. It is expected that calls are charged somewhere between a local or national call if a gateway exists within the network or within the country. In the worst case an internatonal call is charged to Austria if the originating network is not aware of the number range.

Does the VoIP provider get termination fees?

No, because the call is delivered on the Internet.

Does the gateway operator get termination fees?

Yes, according to the national interconnect regime.

Does a VoIP provider has the right to get the call delived via his gateway?

If a VoIP provider is operating a gateway, he has not right to get calls to his subscribers delivered via his gateway. The PSTN is not aware of ENUM assignments to VoIP providers and there is also no assignment of single numbers or number ranges to specific gateways. The decision which gateway to use lies completely within the originating network

Is an ENUM-enabled gateway dedicated to the number range +43780?

No, the gateway may route any call to a number or number range known to be in ENUM. Another ENUM-enabled number range is +87810. The gateway may also route calls to single numbers known to be in ENUM, e.g. if the calling user forces the call to ENUM by dialling a specific access code, or if the number is known to be in ENUM by an IN-query.

What if no compatible service in ENUM exists?

Since the ENUM entries are controlled by the end-user, the end-user may decide not to provide a NAPTR record containing a voice service. In this case the call cannot be completed with cause value "service not available". This may also happen on the PSTN if you call a fax device

What services are currently supported?

The ENUM-enabled gateway from Telekom Austria supports the enumservices sip, h323, voice:sip, voice:h323 and ifax:mailto. It is recommended that other gateways support a similar range of services.

Why is voice:tel not supported?

Voice:tel would require a forwarding of the call to the PSTN, which would incur costs. Since this cost cannot be charged to the calling user and also not to the called user, this calls are rejected with cause value "service not supported", if no other possibility to complete the call exists. If the user want to forward a call to the PSTN, he should use call forwarding with his VoIP provider.

Needs the same gateway to be used for outcalls?

No, on the contrary, it is very unlikely that the same gateway will be used. VoIP providers may not even be aware of the incoming gateways, but they need to provide the user with the capability of out-going gateways for calls to the PSTN. A user may also decide to use a different VoIP provider for outbound calls, although it is recommended to use this number range in CLI display for call-back and calls to emergency services to indicate nomadic usage.

What about number portability?

Number portability in the meaning of the PSTN is somehow not applicable or naturally built-in. The end-user may decide at any time to change the Registrar and also the Name Server Provider, similarly to any other domain name hosting.

The end-user may also decide to change his VoIP (or e-mail) provider by changing the content of the NAPTR record pointing to a given provider. Therefore service provider portability is done by the end-user.

Where do I get a +43780 number?

Anybody may register such a number, for available registrars see enum.at

I registered at www.my-enum.at the number +43 780 203 211, the SIP URI is pointing to my fwd-account. The fee per month with this registrar is 3,60 Euro.

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