Your guide to ISDN 30

Contents

Installing an ISDN line – the beginning 1

Connecting to ISDN 30 2

Delivery Options 3

Customer Interface 7

Connection of CPE & Digital Select Services 8

Description of Digital Select Services 10

ISDN Applications 16

Fault Reporting 18

Now You’re Connected 19

Always in Touch 21

Cost-effective Communications 23

Useful Numbers 25This guide should take only about 15 minutes to read.Please do so because it should save you a good deal of time in the longrun and help you make the most of your ISDN 30 right from the start

For further help and advice on any ISDN applicationsand how to connect them, call our helpline on Freefone 0800 18 15 14or visit www.bt.com/isdn/isdn30/

1

Installing an ISDN line is just the beginning

Many people buy ISDN 30 just for its

voice capabilities. And although these

are second to none, we’d like to show

you how to get more from the service.

That’s why we’ve devised this simple

step-by-step guide. You’ll discover all

the different ways you can use your

system – many of which you may

never have considered before.

For instance, because ISDN is digital,

it can carry so much more information

than a normal analogue telephone line.

You can use it to send and fax

documents, access the Internet or

link up with other computers –

with amazing clarity and speed.

What’s more, ISDN 30 helps you

spread your communications load.

With up to thirty independent 64kbit/s

channels for voice or data per cable,

you can use ISDN to perform different

tasks simultaneously.

Even better, because ISDN 30 is an

integral part of the main telephone

network, you can use it to communicate

with people who have normal analogue

telephone lines.

So start using your ISDN 30 line today.

There’s no end to what it can do for

your business.

Connecting to ISDN 30

ISDN 30 DescriptionISDN 30 is the trade name for BT’sprimary rate service for the delivery ofdigital exchange lines. ISDN 30 is a2Mbit/s digital connection from the BTtelephone exchange to the Customer’sPremises Equipment (CPE).

Each 2Mbit/s system provides:

Up to 30 independent 64kbit/s channels(for voice or data) 1 x 64kbit/s channelfor synchronisation and maintenance and1 x 64kbit/s channel used for signalling.

There are two versions of ISDN 30available:

ISDN 30 (DASS2)This service uses the BT signallingsystem DASS2.

ISDN 30eThe signalling used on this service isQ.931 (ETSI version) which conforms tothe worldwide ITU-T (was CCITT)standard.

Diagram 1 Alternative Routing

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ISDN 30

ISDN 30

BT NetworkiSPBX

LocalExchange

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Delivery Options

Alternative RoutingWith this option, ISDN 30 services arerouted via separate cables from the localservicing exchange. Where possible, thecables may be installed in separate ducts.

Additional one-off charges will be raised if any extra duct or fibre is required.

See Diagram 1 (previous page).

Diverse RoutingWith Diverse Routing, ISDN 30 access will be provided from the user’s localexchange and the nearest appropriatealternative exchange.

Additional one-off charges will be raisedfor any extra duct or fibre used.

Two different numbers will be providedfor both access types.

See Diagram 2.

Diagram 2 Diverse Routing

ISDN 30

ISDN 30

BT NetworkiSPBX

Local Exchange

Secondary Exchange

Delivery Options (cont)

DDI Dual ParentingDual Parenting enables ISDN 30 DDI* tocontinue operating in the event of acustomer’s local exchange processorfailing. This is achieved by connecting thecustomer to two separate local exchangeprocessors, but keeping the same DDItelephone number range.

Whilst both local exchange processorsare working normally, alternate incoming calls are sent to them by theDMSU (Digital Main Switching Unit, part of BT’s core switching network) towhich they are both connected. If there is a failure of either local exchangeprocessor, all incoming calls are sent tothe remaining exchange processor.

* Direct Dialling In [DDI] (see page 15)

The following diagram illustrates this:

4

50% of calls

DMSU

Incoming ISDN 30 DDI calls

Optional diverse route

Exchange Site

Customer Site

50% of calls

NormalExchangeProcessor

AlternativeExchangeProcessor

100%of calls

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ISDN 30 Site Assurance Options 1&2ISDN 30 Site Assurance options enablecustomers to have their ISDN 30(DASS2) or ISDN 30e exchange calls re-routed to an alternative site, in acontracted time, if their normal sitebecomes unusable for any reason.

Customers will call their CustomerManagement Service Centre and will berequired to give a security code, whichwill be verified by BT before thechangeover is carried out. The service is available in two options:

Option 1This option is delivered using the existing ISDN 30 (DASS2) basic diversionservices or ISDN 30e basic forwardingservices. This enables all incoming callsto a customer’s site to be diverted to apre-arranged single number. This couldbe either another of the customer’s siteswhich is to be used as a standby, or athird party provider standby site.

On a customer request the Service Centrewill arrange for changeover of service tothe standby site within one hour.

Basic diversion operates for voice callsonly on ISDN 30 (DASS2) and basicforwarding for voice and data on ISDN 30e, assuming the standby site hasan ISDN 30 service to receive such datacalls. The customer will be charged forthe diverted part of all the calls when thediversion is activated.

Delivery Options (cont)

ISDN 30 Site Assurance Option 2This option is delivered by providing agroup of ISDN 30 channels to acustomer’s standby site, which areconfigured as Incoming Calls Barred(ICB). New ISDN 30 circuits will have tobe ordered at standard ISDN 30connection and rental costs, where thestandby site is off the same servingexchange as the customer site. If thecustomer site is outside of the localexchange area, then Out of Area chargeswill apply.

Network TerminationThe ISDN 30 service terminates on yourpremises on Network TerminatingEquipment (NTE). The type of NTEvaries according to whether the ISDN 30is served over copper cables (transverse screened) or optical fibrecable. The NTE can be either installed ina wall/desk unit which can house 2 NTEsor a rack mounted unit which can houseup to 4 NTEs.

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Customer Interface

ISDN 30 (DASS2)Regardless of the type of NTE fitted onyour premises, a standard interface willbe presented for connection to your CPE.The electrical interface conforms toCCITT recommendations G703 (75 Ohm unbalanced termination). This ispresented by two coaxial cables eachterminated with a BNC plug, conformingto BSI BS9210-N0001 part 2.

These coaxial leads are connected to theNTE at the traffic in (TFC in) and trafficout (TFC out).

ISDN 30eFor the ISDN 30e service, the interfaceconnector is an I.421 socket EN 28877(RJ45) 120 Ohm balanced andsubsequently an ISO 101173 (subject toratification) connector to the CCITT I.421standard.

Power SupplyThe 2Mbit/s NTE fitted when coppercable is used does not require a powersupply as power is line fed from the BTexchange over the copper cable.

The 2Mbit/s NTE fitted when fibre opticcable is used does require a power supply.

Standby PowerIf required, standby batteries can besupplied at a charge, giving up to fivehours backup supply. Alternatively, powercan be supplied from CPE equipment if ithas standby power.

This will give protection in the case of apower failure so that calls can be made,but only if the iSPBX has standby poweras well.

If no standby power is fitted and thepower is switched off to the NTE, servicewill automatically be restored when thepower comes back on.

Connection of CPE & Digital Select Services

The CPE must be approved forconnection to the network. This shouldbe checked with your supplier.

ISDN 30eThe CPE can be disconnected from thenetwork without activating urgent alarms.

ISDN 30 (DASS2)Once the CPE is connected, it is advisablenot to disconnect as automatic alarms willbe activated in the local telephoneexchange reporting a break in service.

Reconnecting the CPE will restart theservice, but if five breaks occur in onehour, the service will need reactivating in

the exchange. This can be done by callingFreefone 0800 800 154 and explainingthe situation.

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Digital Select Services DASS2 ISDN 30e

Calling Line Identity Presentation (CLIP) Yes Yes

Presentation Number Yes Yes

Calling Line Identity Restriction (CLIR) Yes Yes

Connected Line Identity Presentation (COLP) No Yes

Connected Line Identity Restriction (COLR) Yes Yes

Administration provided Basic Diversion – Voice Only Yes No

Administration provided Diversion on Busy or failure of BT bearer – Voice Only Yes No

Administration provided Diversion on Ringtone No Reply – Voice Only Yes No

Administration set up Call Forwarding – for all calls – Voice & Data No Yes

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Digital Select Services DASS2 ISDN 30e

Administration set up Call Forwarding – on Busy – Voice & Data No Yes

Administration set up Call Forwarding – on No Reply – Voice & Data No Yes

Administration provided permanent Outgoing Call Barring (OCB) Yes YesCustomer Controlled Services*

Diversions - not available across DDI (Basic, Busy/Failure, Ringtone No Reply) Yes NoChannel Busying Yes NoCall Barring Yes NoCustomer Controlled Call Forwarding No Yes

Administration provided Selective Outgoing Call BarringAll calls; International calls and Premium Rate Services (PRS); National, International calls & PRS;Operator calls; International, Operator calls & PRS Yes Yes

Administration provide permanent Incoming Call Barring (ICB) Yes Yes

Call Charge Indication (CCI) Yes No

Sub Addressing Yes (6 Octet) Yes (20 Octet)

Call Deflection No Yes

DDI Yes Yes

* For customer controlled services, the CPE connected to the ISDN 30 service must have the capability to activate theseservices. Please contact your supplier for further information.

Description of Digital Select Services

Calling Line Identity (CLI)This facility – available on ISDN to ISDNand analogue (PSTN) calls – enables therecipient to have the number of the callerdisplayed on their terminal. (Assumingthe caller has authorised the release ofhis number and you have subscribed tothe Calling Line Identity Presentationservice.)

Presentation NumberPresentation Number (PN) allows you tospecify a telephone number for yourCalling Line Identity (CLI) for outgoingcalls, which may be different to your

usual telephone number. The specifiedPN CLI will be displayed on the calledparty’s Caller Display equipment ifavailable, or used in conjunction with the1471 service, where calls terminate onanalogue lines, to return calls to you.

You may require this service becauseyour business has separate incoming andoutgoing lines for effective trafficmanagement and resilience. Or perhapsyou want to direct return calls to a moreappropriate number, for example a centralhelp-desk. Before ordering Presentation Number you will need toconsider:

• the regulations surrounding PN withwhich both you and BT are legallyrequired to comply.

• interaction of the BT service with yourown equipment.

• what you will need to do to ensure that calls returned to their Presentation Number are efficientlyhandled.

For more information on Presentation Number includingregulations and the Code of Practice visitwww.bt.com/isdn/isdn30/extra/dss.htm

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Calling Line Identity Presentation(CLIP)This service allows the called customer toreceive the caller’s line identity(telephone number) before answering thecall. The called party will only receive thisinformation if the calling party has agreedto send their number (CLI).

Calling Line Identity Restriction (CLIR)Customers can request that theiridentities (telephone numbers) are notreleased at any time. This service isavailable free of charge when orderedwith the ISDN 30 line.

Connected Line Identity Presentation(COLP)Allows you to confirm that the numberyou have dialled is the number you areconnected to and that you have not beenforwarded to another location.Activation/deactivation of this facility isnot available on a per call basis.

Connected Line Identity Restriction(COLR)You can ask for your telephone numbersnot to be released to callers. Please notethat activation/deactivation of this facilityis not available on a per call basis.

ADMINISTRATION PROVIDED CALLDIVERSION/CALL FORWARDING SERVICES

Basic Diversion/Forwarding – for all calls (Voice & Data ISDN 30e,Voice Only DASS2)All calls incoming to the diverting groupof lines are immediately diverted to thedirectory number that was nominated toreceive the diverted calls.

Diversion*/Forwarding on Busy (Voice& Data ISDN 30e, Voice Only DASS2)Diversion/Forwarding on Busy isprovided so that customers have theopportunity to ensure that any overflow

Description of Digital Select Services (cont)

Diversion*/Forwarding on Busy (Voice& Data ISDN 30e, Voice Only DASS2)(cont)traffic at one location can be answeredelsewhere. ISDN 30 (DASS2) will divertcalls when all channels are busy. ISDN 30ewill forward calls when either all channelsare busy or when a specific DDI extensionis signalled to be busy by the iSPBX.*For DASS2 this also applies to failure of theBT bearer.

Diversion/Forwarding on RingTone/No Reply (Voice & Data ISDN 30e, Voice Only DASS2)Provision of Diversion/Forwarding on

Ring Tone or No Reply means that callswill be diverted to a pre-arrangedtelephone number if the call isn’t answeredwithin approximately 20 seconds.

CUSTOMER CONTROLLED DIVERSIONSSERVICE** – VOICE ONLY (DASS2 ONLY)

This service allows customers to managethe temporary diversion of incoming callsto a group of channels. The customer ischarged for the diverted part of the call.The customer also requires the relevantsoftware on his iSPBX to activate thisservice. (Please check with the supplierof the equipment.)**Not available across DDI ranges.

Basic DiversionAll voice calls incoming to the divertinggroup of lines are immediately re-routedto the directory number that wasnominated to receive these calls.

Diversion on BusyIf all channels within an ISDN 30 (DASS2)group are engaged then calls are divertedto a pre-arranged telephone number, set bythe customer when activating the service.

Diversion on No ReplyWhen activated, all incoming calls thatremain unanswered for approximately 20seconds will be re-directed to the telephonenumber previously set by the customer.

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Customer Controlled ChannelBusying (DASS2 only)Customer Controlled Channel Busyingallows a customer with a group ofexchange lines to reduce the number ofchannels over which the local exchangepresents calls. This service is typicallyused to route all calls incoming to a huntgroup at certain times of the day – toparticular channels.

Customer Controlled Call Barring(DASS2 only)The option to bar different types of callsis under the customer’s control.

Customer Controlled Call Forwarding(ISDN 30e only) This is the Call Forwarding option thatallows you to control the Call Forwardingservice from your PBX / equipment. Youcan choose to forward all calls, on busy, oron no reply. The forwarded part of the callwill be charged to whoever invokes the Call Forwarding facility. You are advised tocheck that your equipment supports therelevant Call Forwarding service offered.Call Forwarding on ISDN 30e allows bothvoice and data calls to be forwarded, CallDiversion on ISDN 30 DASS2 allows onlyvoice calls to be diverted. Only voice callscan be forwarded to normal analogue lines.

Incoming Call Barring (ICB)[DASS2 & ISDN 30e*]ICB restricts use of lines to outgoing callsonly. Customers have a choice of invokingthe service on a per channel basis, oragainst a whole group of channels.

Outgoing Call Barring (OCB)[DASS2 & ISDN 30e*]OCB restricts use of lines to incomingcalls only. Customers have the option ofbarring a single channel, or of barring anentire group.*For ISDN 30e, ICB & OCB are applied acrossall channels and all numbers/DDI ranges

Description of Digital Select Services (cont)

BT ADMINISTRATION CONTROLLEDSERVICES

Selective Outgoing Call Barring (OCB)Also known as: Administration controlled,pre-arranged, OCB.

Selective OCB is available to anycustomer that requires BT to bar certaincategories of outgoing calls.

Call Charge Indication (DASS2 only)With Call Charge Indication, the publicnetwork informs the calling customer’sISDN equipment of the approximate costof a call. The information is not an audible

message, but is a digital informationstream sent down the signalling channelto the user’s equipment for display orstorage at the end of the call – before finalclearing. This, however, will not take intoconsideration any business discountoptions that have been taken.

Sub Addressing (also known asNetwork Address Extension)For ISDN 30 this would apply to equipmentthat supplies ISDN 2e ports to the user.

For ISDN to ISDN calls only, this facilitypermits DASS2 users to add up to six(Alpha numeric characters except #)

Octets to the number they’re dialling.With ISDN 30e, up to 20 Octets can besent to other ISDN 30e or ISDN 2e lines.This allows the caller to select adestination, device or end-point beyondthat indicated by the called nationalnumber (for example a process in a hostcomputer or a device connected to a LAN,or individual devices connected to anISDN 2 port). Assuming your equipmentsupports this facility, the caller may sendhis calling sub address but the called partymust have CLIP to receive this facility.

Call Deflection (ISDN 30e only)Allows you to respond to an incoming 14

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voice or data call by deflecting the call toanother number without answering it. The “forwarded to” number must be ableto accept the calls, for voice calls anynormal number that accepts incoming calls(such as a mobile phone or analogueexchange line) can take the call. The abilityto use this service is dependent upon yourequipment. You can control the criteriathat determines which calls are forwarded,for example on the basis of who the call isfrom, who it is made to, the call type etc.

Direct Dialling In (DDI)Direct Dialling In combines the benefits

of direct access to extension userswithout the need for individual exchangelines to be associated with each user orgoing via the operator.

The principle by which DDI works is thattypically the last six digits of the diallednumber are forwarded to the iSPBX overa group of ISDN lines and are used forcall routing. This enables a range ofpublic exchange numbers to be allocatedto the iSPBX, and for each extension userto have the equivalent of his or her ownexchange line. Frequent callers can thencall directly to the person they wish tocontact.

A number from within the DDI range canbe allocated as the main number for callsto the iSPBX operator. This would be theCompany’s main published number forcallers who do not know the relevant DDInumber of the person or department theywish to contact.

The benefits of DDI• Quick direct access to individuals

without the need to call via the operator.

• Lower work level for the operator,freeing time/resource for other duties.

• Efficient utilisation of the exchange lines.

ISDN Applications

LAN ACCESS and LAN to LANISDN 30 can be used at the central sitefor LAN access from remote locations, viaBusiness Highway or ISDN 2e. This isideal for small sites or home workers whorequire the use of the central resourcesintermittently throughout the day.

Provides flexible bandwidth betweenLANs depending on the amount of data tobe transported.

Call CentresWith the introduction of computer aidedtelephony, ISDN 30 is the only delivery

mechanism that can supply the CLIinformation from ISDN and analogue(PSTN) BT customers. This triggers thedatabase to deliver the customerinformation on screen before the call isanswered. CLIP must be ordered toreceive the CLIs.

Benefits• Fast call answering increases

productivity per position.

• Market analysis of calls and location.

• Call capturing for callers who hang upbefore being answered; they can thenbe called back.

Bandwidth on DemandWith the use of CPE equipmentconnected to the ISDN 30 line, flexiblebandwidth can be achieved from 64kbit/sto 1920kbit/s for large file transfer,videoconferencing and disaster backup toensure there is business continuity.

VoiceHigh quality voice for iSPBXs for low costbulk delivery of exchange lines andfuture proofing facilities.

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ISDN to the DeskISDN 30 can be split to provide digitalservice on extension to a number ofdesktops around your site.

VideoconferencingUsing ISDN, meetings can take placeface-to-face without expensive and time-consuming travel.

Call ChargesAll UK calls regardless of their type;voice, data, text, video, etc. made usingBT’s ISDN services are charged atordinary telephone rates and thereforevary according to duration, destinationand time of day.

For international calls using ISDN, voicecalls are at the standard call tariff butseparate tariffs apply to international datacalls. For details on UK and internationaltariffs please contact your accountmanager or the ISDN helpdesk onFreefone 0800 18 15 14.

Fault reporting

Before reporting a problem to BT,customers are advised that it is in theirinterest to ensure that the fault is on theISDN 30 service and not their CPE. Thefollowing checks should be carried out.

• Check that all plugs are properlyconnected and that power is switched onand directed to all relevant equipment.

• Check that any non-BT maintainedequipment is functioning correctly.

• Remember, if on inspection, BTequipment and lines are found to beworking correctly, you may be liable topay for abortive work carried out by BT.

Fault InformationWhen reporting a fault the followinginformation is required:

1. Directory number(s) of lines on theISDN 30 service.

2. The circuit number i.e. IM/ABC 1234

3. Description of the fault.

4. Name and telephone number of theperson who will be the liaison point forBT regarding the fault.

MaintenanceBusiness repair service level calledPromptCare is provided as standardmaintenance cover for the ISDN 30service.

BT will respond within four workinghours of the fault report between hours0800-1700 Monday to Saturday.

TotalCare is available as a chargeableextra for cover 24 hours a day, 365 days a year. Report any faults to Freefone 0800 800 154.

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Now you’re connected

Quick transfer of files betweencomputersConnect to ISDN and you can send orreceive documents, images, presentationsor reports swiftly. Any document createdon your PC can be sent in this way.

• This application requires: An ISDN TerminalAdapter or card, and e-mail/file transfer software

Instant informationISDN 30 can supply caller identityinformation from ISDN and analogue(PSTN) BT customers. Incomingnumbers are displayed on screen, prior tothe call being answered.

• Please note that Calling Line IdentityPresentation (CLIP) must be ordered beforeyou can receive this service.

Perform several tasks simultaneouslyBrowse the Internet while making aphone call. Download information fromthe Internet while sending informationdirectly to another PC. Or even use thephone while accessing data from anotheroffice. You can also join your channelstogether to achieve a transmission speedof up to 1920kbit/s – so you can accessthe Internet and send large files evenfaster.

Use your PC for speedy callingIf you use a PC-based diary or addressbook, you can often connect yourtelephone directly to your PC. By hittingthe appropriate button next to thenumber you wish to call, you candispense with manual dialling.

Now you’re connected (cont)

Fax faster with laserprint qualityWith Group 4 faxing, you can send laserprint faxes quickly withoutcompromising on quality. For example, a two page price list can be faxed in 2.3 seconds.

• This application requires: An ISDN-compatiblefax machine or PC fax software, available withmost word processing packages. (This will requirean ISDN Terminal Adapter or card).

Rapid Internet access anddownloadingAn ISDN line allows you to surf theInternet and download data much fasterthan with a modem. The time you spendonline is charged at normal phone rates –so you can save money too.

• This application requires: – Access to an ISDN-compatible – Internet Service Provider (ISP).– ISDN-compatible Internet software. – ISDN Terminal Adapter or card.

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Always in Touch

Videoconference around the worldLink up videoconferencing equipment toyour IDSN line, and you can holdmeetings with overseas or UK basedcolleagues without the inconvenience andexpense of leaving the office. Andbecause ISDN is so fast, high-qualityimages are transmitted in real-time.

• This application requires: ISDN-compatiblevideoconference hardware and software. Thiscan be stand-alone or connected to your PC.

Work from homeWith Business Highway or ISDN 2einstalled in the home, you and yourcolleagues can access your office networkand files without ever going there. So youcan work more efficiently – and save timeand money on travel.

• This application requires: ISDN-compatiblerouters at home and in the office, as well as aBusiness Highway or ISDN 2e line at home.

Stay in touch with your customersISDN 30 comes with a number of optionalfeatures to help you make the most ofyour business. What’s more, you can use Calling Line Identity to access the detailsof whoever is calling you. To make it eveneasier for your customers to do businesswith you, use and promote a BT Freefone 0800 number.

Always in Touch (cont)

Link up with other PCs and otherofficesWith an ISDN 30 link, you can extenddigital access to desktops around yourcompany. ISDN is also an invaluable toolwhen you need to work on a project withother offices. By connecting LANs (Local Area Networks), several people indifferent offices can access the sameinformation on their computer screensthrough desktop conferencing. Not onlythat, but you can simultaneously worktogether in updating that information inreal-time.

• This application requires: An ISDN-compatibleLAN router or bridger at each office and anISDN 30 compatible iSPBX.

Keep information flowingUsing your equipment connected to theISDN 30 line, flexible bandwidth can beachieved from 64kbit/s to 1920kbit/s –ideal for videoconferencing, large filetransfer and disaster backup to ensurethere is business continuity.

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Cost-effective Communications

Save time and spend lessAll calls within the UK, whether voice,data, text or video, are charged at publiccall rates. For international calls usingISDN, voice calls are at the standardtariff, whilst separate tariffs apply tointernational data calls.

What’s more, not only is ISDN 30 cost-effective, but it is also time-effective.When using the Internet you’ll spend lesstime on-line – saving you money.

However, it’s important to rememberthat you will be billed for every secondyour ISDN line is open. So be sure toclose the connection once you havefinished your task. This is especiallytrue with applications such as video-conferencing where both the hardwareand software need to be shut down.

Usage tipsIt is very important you check that yourdial-up software, or router, is not set-up tomake unnecessary multiple short calls.You can view the cost of calls made sinceyour last bill by visitingwww.bt.com/billing-payments providedyou have registered online for this service.We advise that you do this soon after yourequipment has been connected to ISDN 30. BT will not refund call chargesraised due to incorrectly configuredequipment. If you do require yourequipment to make lots of short calls thenwhy not consider our Reduced MinimumCall Fee price package (see page 24).

Cost-effective Communications (cont)

Keep costs downNow that you’re connected to ISDN, you don’t need to worry about postal orcourier charges because you can sendinformation direct for the cost of a phonecall. And with videoconferencing, you cancut the cost of travelling to meetings andpresentations.

Incoming calls can also be handled muchmore cost-effectively at the flick of aniSPBX switch. Calls are routed from thecentral switchboard direct to internalphones throughout your company.

Take advantage of BT discountsBT’s Commitment discount packages willhelp you save even more money on ISDNcalls. What’s more, if you make severalshort calls a day, you can take advantageof BT’s Reduced Minimum Call Fee pricepackage. This allows you to save on theminimum amount you spend on each callyou make.

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Useful numbers

If you have any questions relatingdirectly to ISDN 30/30e, please callthe relevant Freefone number below.Alternatively, you’ll find moreinformation about ISDN30 on ourwebsite at www.bt.com/isdn/isdn30/

ISDN HelpdeskFreefone 0800 18 15 14(8.00am-8.00pm Mon-Fri*)

Fault reportingFreefone 0800 800 154(24 hours/7 days a week)

*Opening hours correct at time of publication.Calls may be monitored for quality purposes.

Offices WorldwideThe telecommunications services described in this publicationare subject to availability and may be modified from time to time. Services and equipment are provided subject to British Telecommunications plc’s respective standard conditions of contract. Nothing in this publication forms any part of any contract. © British Telecommunications plc 2002. Registered office: 81 Newgate Street, London EC1A 7AJ. Registered in England No: 1800000. Designed by StrataPrinted in England by Leycol Printers Ltd

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