Avaya Qsig Advantages

Why QSIG? Abstract

Avaya MultiVantage™ Software supports extension-numbering plans up to 7-digits. QSIG (Q-Signaling) networking will be required instead of DCS networking to support private networks with expanded numbering plans enabled by MultiVantage Software. QSIG is Avaya’s premium offer to support enterprise-wide feature-transparent networking. QSIG is also an ISO standard for interoperability between platforms provided by disparate vendors. Avaya Call Processing software, as used in DEFINITY systems, supports 3, 4, or 5-digit extension numbering plans via Distributed Communication Systems software (DCS or DCS+) for virtual networks of Avaya servers. DCS and DCS+ are not being further enhanced but will continuesupported by Avaya on MultiVantage servers as well as on DEFINITY platforms.

to be

(A glossary of related terms is provided on the last page.)

Avaya QSIG Advantages

Many Avaya customers in North America have enterprise-wide Avaya DEFINITY networks that are linked together via Distributed Communication System (DCS). DCS provides a high degree of feature transparency across multiple Avaya systems. This enables multiple Avaya converged communication systems to function as one enterprise-wide communication system. DCS is specific to Avaya. It cannot be used to link Avaya communications platforms to those of other vendors. QSIG, which is defined by the International Standards Organization as an internationally standardized method of networking communication systems, is an alternative to DCS for some Avaya customers. Avaya (including its predecessor companies) is an industry leader in the implementation of QSIG networking. Avaya customers in many regions outside North America are more likely to use QSIG networking than DCS networking. If desirable, it is now possible and in many cases advantageous, for Avaya customers with existing DCS networks to migrate their networks to QSIG. The advantages are summarized below. Expanded Numbering . Many Avaya customers have expressed interest in expanded and more flexible mixed numbering plans. For Avaya DEFINITY systems (systems with software made available earlier than MultiVantage Release 1.1) an extension numbering plan can be 1 to 5 digits. The DCS networked extension numbering plan is limited to 4 or 5 digits1 and DCS trunk access codes are limited to 3

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1 This discussion deals with extension-numbering plans - internal extension numbers that can be appended with area codes, and other codes (such as an RNXs) that are dialed or inserted automatically to extension numbers for 10 or more digit private network or PSTN routing.


digits. While DCS is still supported on platforms running MultiVantage Software, DCS and DCS+ are not expected to be further enhanced to allow expansion of extension numbering plans in a networked environment, nor is it planned for DCS to support greater than 3-digit trunk access codes. In Avaya MultiVantage Software, the extension-numbering plan (per system) will allow for 1 to 7 digits and support QSIG based networking numbering plans. Additionally, MultiVantage Software will enable 4-digit Trunk Access Codes (TACs) as allowed with QSIG. With the Avaya S8700 Server platform’s support of greater port capacities the expansion of particular extension numbering plans may become essential. Prior to the implementation of an expanded numbering plan it is recommended that DCS networks be migrated to QSIG. Services available from Avaya can help to facilitate this migration. Limitations of DCS Networks DCS networks are limited in size and scope. A centralized Intuity voice messaging system can support as many as 20 nodes in a DCS network. DCS networks can support a maximum of 64 nodes under light traffic loads. With 4 centralized Intuity voice messaging systems, each homed to a different node, it may be possible under ideal circumstances for 4 Intuitys to support a 64-node DCS network. The constraint is the bandwidth and capacity of DCS or DCS+ dedicated signaling links or Temporary Signaling Connections (TSCs), which are used with DCS+ when networked over AT&T SDN or WorldCom N-Quest. QSIG networks are not necessarily subject to the same limitations as DCS and DCS+ networks. There are no known limits to the number of nodes that can be supported in an Avaya QSIG network, other than those imposed by the limitation of digits in the numbering plan, routing patterns, connectivity, and software limits imposed that are specific to certain legacy adjuncts. For those enterprises that require scalability from small to the very largest enterprise-wide network implementations, QSIG networking may be the appropriate facilitator. The number of nodes that can be supported in a DCS network is subject to limitations imposed by legacy BX.25, TCP/Ethernet, or PPP signaling channel bandwidth, as well as system limits for links and hop channels. There is a three-hop limitation between nodes (An example of 3 hops is A-B-C-D, where each dash represents a hop) The bandwidth limitation for signaling links is between 9.6 Kbps (for legacy data modules used with BX.25) and 56 or 64 Kbps bandwidth available to support common channel signaling links in non-ISDN DS1 or PRI “D”-channels. These signaling links can also be subject to latency in the network, which affects performance and bandwidth consumption. DCS+ is an improvement over traditional DCS. There are two basic types of DCS+ networks. The most commonly occurring type involves dedicated direct T1 or PRI connections between nodes. The second type is when ISDN trunks are established between each node and the point of presence of the service provider’s ISDN network (AT&T SDN or MCI N-Quest). In this environment TSCs are established as needed to support active calls between nodes. The TSCs can reduce the amount of bandwidth and associated PSTN costs needed to support feature-transparent networks, since dedicated ISDN private-line links between nodes are not required. (There is no Avaya QSIG equivalent to this virtual type of DCS+ at this time. See “Future QSIG Replacement For Non-dedicated DCS+” below for information about future capabilities.) DCS / QSIG Feature Deficit With the introduction of support for Leave Word Calling to provide message-waiting indication over QSIG, it is planned that the feature deficit between DCS/DCS+ and QSIG will essentially be eliminated in Avaya MultiVantage Software Release 1.2. Leave Word Calling (LWC) is a feature RFL Avaya, Inc All rights Reserved, 2002 Avaya QSIG Advantages LPH 8/1/2002 of 9


that allows an internal telephone user to leave a “return call” message for another internal telephone user or to cancel a previously sent LWC message. LWC is initiated by entering a feature access code, or depressing a feature button on a multi-button set, followed by an extension number. Once LWC is completed a message-waiting light is activated and a callback message can be activated on the recipient’s telephone. A similar procedure can be used to deactivate message-waiting indication.

This functionality has long been available to users on a single DEFINITY or for users in a DCS network. The planned Avaya QSIG enhancement of LWC in MultiVantage Software 1.2 will extend this functionality to enterprise-wide networks with QSIG as well as those with DCS. For networks that are mixed DCS and QSIG, or in transition from DCS to QSIG, interworking of features between the protocols is enabled. LWC integration with MultiVantage or DEFINITY software is required for support of some voice messaging platforms, such as Avaya (formerly Octel) Aria systems. (This limitation does not pertain to Intuity, Serenade, Unified Messaging, or other Avaya voice messaging systems, which can be integrated with QSIG and expanded numbering plans.) QSIG Over IP Trunking IP trunking has become a popular, cost-effective, and reliable method for supporting DCS and QSIG networking. This is particularly true when traffic can be routed over IP networks via shuffling, which reduces the need for TDM resources. Avaya’s implementation of IP trunking provides the ability to route calls over PSTN facilities as a fallback in the event that the IP network degrades, as measured by a selectable threshold for latency. QSIG will become increasingly important for networking of converged voice over combinations of PSTN, IP, Frame Relay, and ATM networking infrastructures. QSIG networking is advantageous in complex networks when voice must be compressed and decompressed, or companded multiple times for codec translation, to traverse nodes, or for voice messaging storage. QSIG route optimization using path replacement and rerouting techniques can potentially reduce the number of hops required to connect a call. Possible voice quality degradation is avoided by the use of these QSIG routing techniques. It is possible to implement IP trunking between Avaya MultiVantage servers and DEFINITY platforms with low latency and very good voice quality. The performance of IP trunking over the WAN or VPN depends on deployment of adequate bandwidth, a QoS policy, and the performance characteristics of the multi-services networking infrastructure that supports it. Numerous Avaya customers already have deployed DCS and QSIG networks that rely on IP trunking. At present, Avaya IP Trunking can only be used to connect Avaya ECLIPS converged communication platforms. It is planned that in a future release, Avaya’s IP trunking will support an industry-standard format (ITU H.323 M.1 Annex) that will allow tunneling of QSIG over IP trunking between different vendor’s communication systems. Compatibility between vendors’ systems over IP trunking may become a possibility if and when Avaya and the other vendors implement and test this capability. Private Networks Vs Public Networks At present, QSIG networking connectivity is limited to direct connections between communications platforms. If and when service providers become capable of supporting QSIG virtual private networks, QSIG may become an increasingly preferred networking solution for Avaya’s customers. Avaya intends to continue to support and make available DCS and DCS+ as our non-standards based and entry-level offers for feature-transparent networking between Avaya platforms.

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International Open Standard Vs Vendor-Specific QSIG is an international industry standard. DCS and DCS+ are Avaya-specific networking protocols. Avaya’s active support and promotion of internationally recognized standards is a strong investment protection message to multi-location customers. For Avaya-enabled enterprises that acquire businesses that utilize other vendors’ communications platforms, QSIG may be the enabler for enterprise-wide communications networking. These mixed networks can share Avaya voice messaging platforms. Avaya’s QSIG implementation assures DCS-like functionality as well as standard QSIG features. Avaya’s experience and interoperability capabilities with QSIG are well established where Avaya products have a presence. Avaya products are supported in 90 countries. Future QSIG Replacement For Non-dedicated DCS+ DCS+ customers have been taking advantage of reduced networking costs because DCS+ uses Temporary Signaling Connections (TSCs) over the public switched telephone network (PSTN); this facilitates optimal use of PSTN facilities. Basic DCS requires expensive dedicated trunking, typically dedicated T1 or E1 links between nodes. Avaya QSIG networks presently require dedicated connections between communications platforms, much like basic DCS. QSIG will become a viable alternative for DCS+ over the ISDN PSTN once the feature “Separation of Bearer and Signaling” (SBS) is available in a future release of MultiVantage software. The ability to provide signaling over an IP network will provide the benefit of feature transparency while maximizing the capability of ISDN PSTN facilities to assure toll quality voice traffic. This enables a functional equivalent to DCS+ without requiring dependence on the limited set of specific network services providers that provide compatibility with DCS+. A typical SBS call flow is illustrated below. Note that all messages shown are the SBS call signaling messages over the SBS IP WAN link. The SBS signaling link implementation is not based on an international standard, as is QSIG itself. Avaya’s planned SBS capability is intended to support a network of Avaya platforms (in the absence of comparable international standards to accomplish this function).

Each SBS call has two components: an IP session to carry the SBS call control and QSIG private networking signaling information, and a bearer call over a switched public network. SBS will associate these two component calls at the originating and terminating MultiVantage platforms so that the call looks like a “normal” call to the end users. SBS calls will support all QSIG features currently supported by Avaya’s MultiVantage Software. SBS calls can be interworked over ISDN to non-SBS networks in the same fashion that Avaya solutions currently interwork QSIG to non-QSIG networks.

For each SBS call, an available “SBS Extension” is used to coordinate between the signaling IP call and the circuit-switched bearer call. A sufficient pool of these extensions must be configured based on busy hour call traffic capacity. Each SBS Extension is used for a short time during the SBS call setup phase. SBS Extensions are “virtual” extensions in that they are not administered without associated hardware. Despite the absence of actual telephones, these SBS Extensions do reduce the pool of available administrable extensions on each system. Each of the SBS Extensions must be based on a real DID number leased from the local exchange company. SBS capabilities for MultiVantage Software will be introduced in phases. Support for SBS will require additional hardware. A quantity of TN799DP C-LANs (or equivalent support on G700 media gateways), IP Trunk port licenses, and other components may be required.



QSIG over IP Trunks may be preferred to SBS for some implementations. SBS is not suggested for those Avaya-enabled enterprises that already have IP trunking deployed to support DCS or QSIG networks. IP Trunks are administered as virtual connections between two IP endpoints that must be defined by IP endpoints. With IP trunking, both bearer and signaling is carried over a private WAN, rather than over a public or private ISDN network using the PSTN. Illustration: Proposed Future Avaya QSIG Separation of Bearer and Signaling Capability (Planned for a Future Avaya MultiVantage Software Release)

“SBS” IP SignalingWAN Link

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FINITY ECS customers upgrading to MultiVantage Software cf networking features into two packages. Avaya DEFINITY syntage Software will automatically receive either the Advancedpending on which features were licensed previously. The Mu

upgrade offer for those systems with DCS, DCS+, Wideband, r at least one of the features listed in the “Networking Bundle Fw) will receive a license for the entire Networking bundle for thsly licensed. The Networking bundle includes QSIG Supplemd Attendant Service Main or Branch, QSIG VALU Avaya (DCS

ce Mail Integration, and QSIG Path Replacement, in addition ton the Advanced bundle. This means that DEFINITY systems wtware being upgraded to MultiVantage software will be licensenal charge other than costs associated with the system softwaexcept for those charges associated with adding new ports andlication software that is required or useful in the implementatioDN Primary Rate, Uniform Dial Plan, and Private Network Acc bundle. The Networking bundle includes everything provideding table lists the features included in the Advanced and Netw

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PRI Access

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an take advantage of the stems that are upgraded bundle or the Networking ltiVantage Software or Centralized Attendant eatures” column in the

e same number of ports entary Services, QSIG features over QSIG), all of the features ith existing DCS or

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Avaya QSIG Advantages of 9


Advanced Bundle Features Networking Bundle Features All standard R10 features, including Uniform Dial Plan and Telecommuting, plus: ISDN Primary Rate Attendant Vectoring QSIG Basic (display of calling party name and number information) Echo Cancellation for PRI, E1, or T1 TN464GP interfaces Multilocation routing Meet-me Conferencing Automated Attendant Holiday Vectoring 5 Free EC500 User Licenses Centralized Voice Messaging (via Mode Code only) Integrated Announcements (with S8100 Server only) Private Network Access (with Automated Alternate Routing)

All features in the Advanced bundle, plus: DCS and DCS+ DCS Wideband QSIG Supplementary Services QSIG VALU Avaya (DCS features over QSIG) QSIG Path Replacement QSIG Voice Messaging Integration QSIG Centralized Attendant Service Main or Branch Centralized Attendant Service for Tie / Release Link Trunks

Avaya Implementation Support Services Migrating a network from DCS to QSIG involves provisioning, planning, project management, administration of software options, and coordination. Avaya professional services resources are available to facilitate expedient migration of existing networks to expanded numbering plans and QSIG with a minimum of disruption to existing operations. Please contact your Avaya or Avaya Business Partner representative for further information.



QSIG Glossary2

Term or Acronym Definition

ACP Avaya Call Processing Aria An Octel voice-messaging platform. ATM Asynchronous Transport Mode - a dedicated-connection switching

technology that organizes digital data into 53 byte cell units and transmits them over a physical medium using digital signal technology. Individually, a cell is processed asynchronously relative to other related cells and is queued before being multiplexing over the transmission path.

BX.25 A version of the CCITT X.25 protocol for data communications. BX.25 adds a fourth level to the standard X.25 interface. This uppermost level combines levels 4, 5, and 6 of the ISO reference model.

C-LAN TN799 Circuit Pack - Controlled-LAN. Provides TCP/IP connectivity over Ethernet or PPP to adjuncts. This circuit pack in a DEFINITY or MultiVantage port network serves as the server’s network interface. It terminates IP (TCP & UDP) and relays those sockets and connections up to the DEFINITY or MultiVantage server. The C-LAN serves as an H.323 gateway.

CMS Call Management System – an Avaya adjunct processor used to provide reports on contact center activity.

Codec Coder/decoder or compressor/decompressor - a hardware or software device, typically implemented in Digital Signal Processor firmware, which converts data from one format to another.

Companding A commonly used method to digitally encode sound. DCS Distributed Communication System – an Avaya telephony capability

that enables feature-transparent networking across Avaya converged communications platforms.

DCS+ DCS networking capability that supports virtual feature-transparent networking.

E1 E1 (or E-1) is a European digital transmission format devised by the ITU-TS and given the name by the Conference of European Postal and Telecommunication Administration (CEPT). It’s the equivalent of the North American T-carrier system format. E2 through E5 are carriers in increasing multiples of the E1 format. The E1 signal format carries data at a rate of 2.048 million bits per second and can carry 32 channels of 64 Kbps each. E1 carries at a somewhat higher data rate than T-1 (which carries 1.544 million bits per second) because, unlike T-1, it does not do bit-robbing and all eight bits per channel are used to code the signal. E1 and T-1 can be interconnected for international use.

ECLIPS Avaya’s Enterprise Class IP Solutions Feature Deficit A term used to describe the absence of directly comparable features

in one offering as compared to another. G700 Media Gateway An Avaya MultiVantage H.248 Media Gateway that is used with

S8300 and S8700 Media Servers. Intuity An Avaya voice-messaging platform. IP Trunking Communications channels between converged communications

platforms that use Internet Protocol.


2 The definitions listed in this glossary apply to usage of the term in this document.



ISDN Integrated Services Digital Network is a network protocol based on ITU Q.931 specifications to provide intelligent networking functionality

ITU International Telecommunications Union - Formerly known as International Telegraph and Telephone Consultative Committee (CCITT), ITU is an international organization that sets universal standards for data communications, including ISDN. ITU members are from telecommunications companies and organizations around the world.

LWC Leave Word Calling is a DEFINITY or MultiVantage message used to activate MWI lamps from a station or messaging system using a Feature Access Code

MultiVantage Software Avaya’s MultiVantage™ Software is highly scalable and reliable voice application software with rich call processing and contact center functions and widely accepted application-programming interface that supports a range of Avaya and third-party applications.

MWI Message Waiting Indication is the functionality of lighting and darkening lamps on telephones to indicate whether the user has a message.

N-Quest MCI/WorldCom features for provision of User-to-User Services. Needed to transport DCS+ messages in the MCI/WorldCom PSTN

Octel The name of the voice messaging products company (and its products) acquired by Lucent, which later became part of Avaya.

Path Replacement A method used to minimize the number of links in a communications session involving more than two nodes.

PRI Primary Rate Interface - A standard ISDN frame format that specifies the protocol used between two or more communications systems. PRI runs at 1.544 Mbps and, as used in North America, provides 23 64-kbps B-channels (voice or data) and one 64-kbps D-channel (signaling). The D-channel is the 24th channel of the interface and contains multiplexed signaling information for the other 23 channels.

PSTN Public Switched Telecommunications Network QSIG Standards based multi-vendor private networking protocol based on

Q.931 standards (ISDN) Rerouting A method used to minimize the number of links in a communications

session involving more than two nodes. RNX Route-number indeX – a private network office code used to

designate nodes. S8300 Media Server An Avaya media server, which can be used with G700 Media

Gateways. The Avaya line of media servers provides a robust application platform based on industry standard operating systems to support distributed IP networking and centralized call processing across multi-protocol networks

S8700 Media Server An Avaya media server provided in pairs, which support Avaya G600, G700, MCC1, and SCC1 media gateways. The Avaya line of media servers provides a robust application platform based on industry standard operating systems to support distributed IP networking and centralized call processing across multi-protocol networks.

SBS Separation of Bearer from Signaling – the separation of the QSIG signaling channel and the QSIG communications payload channel to provide a low cost “virtual private network” with high voice quality.

SDN Software Defined Network -Trade name of AT&T for ISDN Software Defined Network, a VPN offering that is needed to support DCS+ virtual networks.





Serenade An Octel voice-messaging platform. Shuffling Avaya MultiVantage software provides IP to IP direct audio

connections to save system resources, such as channels on the media processor and TDM bus time slots, and to improve voice quality by eliminating extra coder/decoder functions on the media processor. This is sometimes called “shuffling.” The end user does not have to take any action to invoke audio shuffling. The gateway will shuffle, if possible, after a point-to-point call is established between two endpoints, provided both endpoints are capable of handling shuffling.

T1 The T1 (or T-1) carrier is a commonly used digital line in the United States, Canada, and Japan. In these countries, it carries 24 pulse code modulation (pulse code modulation) signals using Time-Division Multiplexing at an overall rate of 1.544 megabits per second.

TDM Time-Division Multiplexing - Multiplexing that divides a transmission channel into successive time slots.

TSC Temporary Signaling Connection – an ISDN User-to-User message type for exchanging call associated and non-call associated messages. Used by DEFINITY and MultiVantage Software to transport DCS+ messages in the ISDN – PRI protocol.

Unified Messaging A platform that lets users send, receive and manage all email, voice and fax messages from any telephone, PC or information device.

VPN Virtual Private Network. In the context of this document, this means emulating feature rich private voice networks while using the PSTN for transport. A virtual private network (VPN) is a private data network that makes use of the public telecommunication infrastructure, maintaining privacy through the use of a tunneling protocol and security procedures. A virtual private network can be contrasted with a system of owned or leased lines that can only be used by one organization. The concept of the VPN is to give the entity the same capabilities at much lower cost by using the shared public infrastructure rather than a private one. Network providers have provided secure shared resources for voice messages. A virtual private network makes it possible to have the same secure sharing of public resources for data. Enterprises today can using a Virtual Private Network for both extranet and wide-area intranet. Using a virtual private network involves encrypting data before sending it through the public network and decrypting it at the receiving end. An additional level of security involves encrypting not only the data but also the originating and receiving network addresses. VPN software is typically installed as part of a company’s firewall server.

WAN Wide Area Network – a network distributed over a large geographic area.

© 2002 Avaya Inc. All Rights Reserved. Avaya and the Avaya Logo are trademarks of Avaya Inc. or Avaya ECS Ltd., a wholly owned subsidiary of Avaya Inc. and may be registered in the U.S. and other jurisidictions. Avaya trademarks identified by ® and ™ are registered trademarks or trademarks, respectfully, of Avaya Inc. All other trademarks or registered trademarks are the property of their respective owners.

Avaya Qsig Advantages

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