All guides
Every guide follows the same order: the likely answer first, then where the call breaks, then safe checks, then the reference detail. Start with the system you have, or with the symptom you can see.
Avaya IP OfficeGuides liveMitel MiVoiceGuides liveCisco CUCMGuides liveNEC UNIVERGEGuides liveGlossaryTerms explained
PBX Help Hub is an independent guide to the business phone systems (the PBX) UK organisations already run. Most guides here start from a symptom (calls going to the wrong person, phones not ringing, voicemail answering too soon) and lead you to the setting that causes it, with read-only checks first and a clear point at which to call an engineer.
The guides are grouped by system and by topic below. If you're not sure where to start, the call path explains everything: a call arrives on a line, is matched to a route, is switched by a time profile, rings a hunt group, reaches a user, and ends at voicemail if nobody answers. Every fault sits at one of those six stages. Planning a change instead? Start with Repair, upgrade or replace your IP Office?, the ISDN switch-off, or check your switch-off date.
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IP Office: call routing
Interactive diagnosticCalls not reaching the right peopleWrong person, nobody rings, or calls fail: find the stage in four questions.DiagnosticHunt group not ringing, or ringing the wrong peopleMembership, ring mode, service mode and member status, checked in order.Reference + animationIncoming call routes: how matching and fallback workHow IP Office picks a destination for each number dialled.DiagnosticNight service or time profile not switchingOut-of-hours handling that starts too early, too late or never.GuideCalls going to voicemail too soon or at the wrong timeNo-answer time, forwarding and the voicemail fallback.GuideAuto attendant sends callers to the wrong placeMenu actions, default actions and out-of-hours menus.
IP Office: lines and call quality
DiagnosticSIP trunk down or not registeringWhen every call fails: line, network, registration and carrier.Guide + animationOne-way audio or no audio on callsWhy one side can't hear, and the network settings behind it.GuideCalls dropping after a few minutesUse the exact time a call drops to find the cause.
Avaya phones and handsets
HubAvaya desk phone guides: find your modelIdentify your handset and find its official user guide.GuideHow to forward calls on an Avaya desk phoneForwarding types, how to check them, and how they cause misrouting.DiagnosticAvaya IP phone stuck on Discover or not getting an addressPower, network, address, then call server: four checks in order.GuideReset an Avaya phone safelyRestart, clear or factory reset: what each one changes.
IP Office: lifecycle and decisions
Dated referenceIP Office 500 V2: support status and options for UK ownersWhat the support status means for you, and your options.Decision guideRepair, upgrade or replace your IP Office?A fair comparison: keep, upgrade, 3CX, Teams Phone or hosted.GuideIP Office Manager: read-only checks before you change anythingLook safely: what to open, what to note, what never to save.GuideBack up your configuration safely before any changeThe one habit that makes every other fix reversible.
Mitel
Cisco
NEC
Glossary
Definition + diagramWhat is a PBX phone system?The business phone system in plain English: what it does, the types, and how to tell which you have.Definition + diagramWhat is ISDN?The digital phone line many business systems still use, ISDN2 and ISDN30, and why it's being switched off.Definition + diagramDDI (direct dial-in) explainedThe number a caller dials, and why routing depends on it.Definition + animationHunt group types explainedCollective, sequential, rotary and longest waiting, side by side.Definition + animationTime profiles and night service explainedHow a phone system knows it's out of hours.Definition + diagramSIP trunks explainedThe internet phone line that's replacing ISDN.Definition + diagramVoice VLANs and DHCP for desk phonesHow a desk phone finds its network, address and call server.
Switch-off and dependencies
Interactive plannerHow to check your switch-off date (and what to do next)Find out when your lines move to digital, and a plan for each timeframe.GuideISDN switch-off: what it means for your on-site phone systemWhat changes, what doesn't, and what to check before your line moves.Interactive toolAnalogue dependency checker: lifts, alarms, door entry, card machinesTick what's on your premises and see what needs checking.
Safe working and trust
Checklist (copyable)Before you call support: the evidence to collectA copyable fault log your engineer can work from straight away.GuideEscalate safely: when to stop and call an engineerThe signs that a fault needs a specialist now.Editorial policyHow we write and check our guidesWho reviews each page, what we test and how we keep it current.ResourcesFree infographics and checklistsPrint, pin or embed our one-page guides, free with credit.
Services
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One-page summaries of each guide, free to print, pin or share with credit. Click one to open its guide, where you can download the PNG.
