Boaz Michaely's Home Page at ITU

The work below work was done during 2000 – 2001 and is now abandoned.

Enhanced Services Zone - work in progress

Introduction

IP Telephony service providers may wish to use equipment from different vendors, and yet organize their network as a single administrative domain. When considering enhanced services such as Call Answering with Messaging, it is desirable to operate the service equipment as an independent zone, rather than configuring the low level equipment to be managed by the core network gatekeeper (e.g. as a media server).
Under this scheme, call control signaling channel is established between the forwarding element and the Service Zone, using inter-zone communication procedures.

By configuring the service equipment to operate independently, several important advantages are achieved:

Releases vital resources from the core network to take other calls. Note that Calls under enhanced services (such as leaving or retrieving voice mail) have different behavior patterns than person-to-person calls. A well engineered Service Zone can accommodate this behavior better that the core network GK (e.g. in terms of load balancing, scalability and availability)
Enhanced Service equipment typically have specialized resources of which the core GK is unaware, and thus unable to manage. The reporting and management capabilities within RAS are tailored for gateways, and do not encompass the needs of the Service Zone resources.
Migration of field proven Service Zone equipment from PSTN environments is made much easier by requiring only a thin interface (of inter-zone communication), while the enhanced service subsystems remain intact. This allows the customers to preserve their investment in enhanced services equipment, provisioning, operations, etc. as well as reduce the business risks, while migrating to VoIP networks.

Requirements from the standard for supporting the Service Zone

· End-to-end continuity - the power of knowledge

It is important to notice that when the Service Zone Border Element makes the device selection, it may require the full information for the specific call being forwarded, such as caller ID, original called number, and reason of redirection. All of this information is available in the forwarding GK, in case it is a Gatekeeper Routed network. It is therefor essential, that H.323 supplementary service information (such as H.450.3) be available through the these messages as proposed herein.

It has also been noted, that the decision criteria may include the type of media capabilities which are known to be required for this call. Having all of the call related information available at the first point of negotiation (AccessRequest) is a powerful scheme for optimizing resource utilization within the Service Zone. This scheme is actually supported in SIP networks.

· Support for Fast Connect

In order to shorten the time of negotiation, and minimize the burden from the network gatekeeper, it is also necessary to include the Fast Connect information in the inter-zone negotiation. This way, the Service Zone BE may assure that the selected resource will support Fast Connect, and in fact give it a head start in preparing to receive the incoming call.

· Service Zone availability

High availability of the Service Zone may be achieved by establishing a service relationship and identifying alternate border elements within the Service Zone. A N+1 architecture of BEs in the Service Zone may be used to provide high availability with unlimited growth capabilities.

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H.246 Annex D : IPT-IN Interworking

The scope of this yet-to-be-defined standard is to specify the means for an H.323 GK to access an IN SCP in order to exchange information required to provide IP Telephony services which cross IN networks.
The following functions need to be supported:

Charging and accounting arrangements between the IN provider and the IPT provide
Common Identification, Authentication and Authorization mechanisms
Security - including encryption arrangements, screening("policing")
SCP selection mechanism. (i.e. handling Global Title)
Signalling gateway requirements.

Contributions are solicited !

Official Terms of Reference (Berlin Aug 6, 99 ; size 41K)

VocalTec/Marconi proposal which led to this (Berlin Aug 2, 99 ; size 89K)

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