Key Takeaways
- This contact centre platform comparison covers Mitel, Avaya, Five9 and 8×8 across deployment, AI capability, integration and cost — the four factors that matter most when switching.
- Five9's Voice AI Agents offer the most advanced agentic AI in 2026; 8×8 favours agent-facing prompts over voice-first automation.
- Five9 is a contact-centre-only platform built for voice; 8×8 bundles contact centre, unified comms and APIs, with workforce management included as standard.
- Mitel users closing an AI gap should compare Five9 or 8×8 — both are cloud-native with AI built into the core platform, not bolted on.
- Written by Kris Graham - Account Director
- Connect with Kris on LinkedIn
This guide assumes you’re already running a Mitel estate and comparing it against Avaya, Five9 and 8×8. I wanted to share a useful overview on what each platform can actually do today, deployment model, AI and automation, integration and maintenance burden, and cost structure, rather than vendor history or ownership status.
Mitel, Avaya, Five9 and 8×8 contact centre platform comparison at a glance
| Mitel | Avaya | Five9 | 8×8 | |
|---|---|---|---|---|
| Deployment | Private instance, on-premises, hybrid cloud contact centre add-on from 2026 | Legacy on-premises common, or Avaya Infinity (cloud-native, hybrid, on-premises) | Cloud-native, multi-tenant, since 2001 | Cloud-native, unified with UC and comms APIs |
| AI approach | Call routing and workforce management; deeper AI delivered via partner ecosystem (e.g. Five9) | Tandem Care model: conversational, generative and agentic AI working alongside human agents | Voice AI Agents (launched June 2026): reasoning, action-taking, native to the platform | Smart Assist and AI Studio: agent-facing prompts, low-code AI agent building |
| Integration model | Open standard, first major CCaaS platform to adopt MCP | Open standard, first major CCaaS platform to adopt MCP | Native, shared data and orchestration across the CX platform | Native across contact centre, UC and comms APIs in one environment |
| Maintenance burden | On you or your support partner: patching, hardware refresh, security hardening | Legacy estates carry the same burden as Mitel; Infinity removes it | None on your side, updates ship centrally | None on your side, updates ship centrally |
| Best fit | Businesses wanting a well-supported Mitel estate, long-term or as a step before adding cloud AI | Regulated or infrastructure-sensitive sectors modernising in place | Voice-primary businesses wanting advanced agentic AI with governance | Businesses wanting unified comms and contact centre with broad channel coverage |
Mitel Contact Centres
Deployment: private instance, on-premises, extending to hybrid via a 2026 cloud contact centre add-on.
Mitel’s platforms, MiVoice Business, MiVoice Office 250 and MiVoice Connect, are built as private instance systems. Patching, security hardening and hardware refreshes sit with you or your support partner, and every piece of modern capability has to be added on top rather than arriving built in. MiVoice Business remains Mitel’s actively developed go-forward platform, with no published end-of-life date, so if your estate sits there today, there’s no deadline forcing a decision on its own.
Mitel’s contact centre AI is built around call routing and workforce management. Deeper agentic AI capability is delivered through Mitel’s partner ecosystem, including Five9, rather than as native functionality, and its 2026 hybrid release, which lets you keep a Mitel PBX on-premises while running the contact centre itself in the cloud, gives estates a route to that capability without a full platform migration.
Every AI or omnichannel capability you add on top is another vendor, another integration, another thing to patch and keep compatible. That’s the private instance cost structure in practice, licensing plus maintenance plus every bolt-on, rather than one predictable line.
Best fit: Mitel is a great fit for businesses who want a well-supported Mitel estate, whether that’s a long-term decision or a considered step before layering in cloud AI capability alongside it.
Avaya Contact Centres
Deployment: legacy on-premises estates still common, alongside Avaya Infinity, a newer platform supporting cloud-native, hybrid and on-premises deployment.
A meaningful share of Avaya estates still run on legacy, on-premises platforms with the same private instance limitations as legacy Mitel, patching, hardware refreshes and integration overhead sitting with the customer. Avaya has since launched a genuinely different platform, Avaya Infinity, in 2025, a unified CX platform built to support cloud-native, hybrid and on-premises deployment side by side. What Avaya means today depends heavily on which generation of the platform you’re actually running, worth clarifying early in any conversation.
Avaya Infinity is built around a Tandem Care model, layering conversational AI, generative AI and agentic AI so human and AI agents work as one coordinated system. According to Avaya’s own product announcements, it’s the first major enterprise contact centre platform to adopt the Model Context Protocol, an open standard that connects it to AI models from any provider rather than locking customers into one vendor’s tooling. Avaya has also announced Avaya Nexus, a mission critical voice platform aimed at government, defence, healthcare and other high-stakes sectors, due late 2026, designed to layer AI on top of existing infrastructure rather than force a full migration.
That flexibility is genuinely useful if data sovereignty, regulatory compliance or existing infrastructure investment are driving the decision, though it means the AI gap conversation with Avaya depends heavily on whether you’re comparing against a legacy estate or against Infinity itself.
Best fit: Avaya is a great fit for businesses who operate in regulated or infrastructure-sensitive sectors wanting to modernise in place rather than migrate everything to a public cloud platform.
Five9 Contact Centres
Deployment: cloud-native and multi-tenant, no infrastructure to manage on your side.
Five9 has been cloud-native since 2001, a claim the company repeats consistently across its own product and investor materials, so there’s no private instance to maintain, no hardware refresh cycle, and no patching schedule sitting with your team. Updates and new capability ship centrally to every customer on the platform rather than through a planned upgrade project.
Five9’s latest release, Voice AI Agents, launched in June 2026, is purpose-built for the agentic era. Per Five9’s own launch announcement, it reasons through customer requests, takes action across enterprise systems, and hands off to a human agent with full context when needed, rather than the scripted, rules-based virtual agents most legacy platforms still rely on. It’s built with enterprise-grade governance in mind, guardrails, automated post-call evaluations and a feature called LLM blinding that stops sensitive data being seen or used by the underlying model, which matters if you need to prove control over how AI is being used, not just that it’s being used.
The AI capability is native to the platform rather than bolted on, sharing data and orchestration with the rest of the Five9 estate, which is the practical difference your IT team will notice first, one system to integrate rather than several.
The trade-off is scope. Five9 is a contact centre platform, not a unified communications platform, so businesses wanting voice, contact centre and UC bundled together in one environment, the way 8×8 packages them, will still need to run a separate UC solution alongside it.
Best fit: Five9 is a great fit for businesses where voice is the primary channel and who want the most advanced agentic AI capability available today, with governance controls that satisfy a regulated environment.
8×8 Contact Centres
Deployment: cloud-native, unifying contact centre, unified communications and communications APIs in one platform.
8×8 takes a different shape to Five9. Rather than a contact centre platform alone, it combines contact centre, unified communications and communications APIs into what it calls the Platform for CX, so voice, video, chat, SMS, WhatsApp and RCS all sit in one environment rather than needing separate tools stitched together.
8×8’s AI is built across the agent workspace. Smart Assist gives agents real-time prompts and automated post-call summaries, and 8×8 AI Studio lets teams build and deploy voice and digital AI agents in plain language rather than through complex configuration. Workforce management now comes bundled with every 8×8 Contact Centre plan rather than as a separate purchase, a meaningful difference if forecasting and scheduling tools are currently a separate line item in your stack.
The breadth is the trade-off worth knowing, and it cuts both ways. 8×8 covers more channels and use cases in one platform than most competitors, and as with most platforms offering both breadth and depth, the most advanced AI and analytics features sit in higher pricing tiers.
Best fit: 8×8 is a great fit for businesses wanting unified comms and contact centre together, broad digital channel coverage including WhatsApp and RCS, and workforce management included as standard.
Contact Centre Platform FAQs
It depends on what’s driving the decision. A well-supported Mitel estate remains a legitimate long-term choice, particularly where the platform is meeting the business’s needs today. If closing the AI gap is the priority, Five9 or 8×8 are worth comparing directly, both are cloud-native with AI built into the core platform rather than added on.
Five9’s Voice AI Agents, launched June 2026, and Avaya Infinity’s Tandem Care model are both built around voice-native, reasoning and action-taking AI. 8×8’s AI Studio and Smart Assist take a different approach, agent-facing tools built into the workspace rather than voice-native agentic AI, better suited to businesses prioritising broad channel coverage over voice-first automation.
No. A significant share of existing Avaya estates run on legacy on-premises platforms, but Avaya Infinity, launched in 2025, supports cloud-native, hybrid and on-premises deployment side by side. Whether “Avaya” means the legacy estate or Infinity depends entirely on which generation a given business is running.
Five9 is a contact centre platform built cloud-native from 2001, with its AI strategy concentrated on voice-native agentic capability. 8×8 combines contact centre, unified communications and communications APIs into a single broader platform, with wider digital channel coverage (including WhatsApp and RCS) and workforce management bundled as standard. Here’s a useful comparison page.
