Upgrade or replace your PBX?

The lifecycle decides a lot

Mitel’s lifecycle policy is a good starting point:

• Active Software Assurance or a subscription is required for new versions, service packs and fixes.
• Bugs are fixed in the latest version. Critical bugs are fixed in the previous major version for up to 18 months after the new one is released.
• End of sale is announced at least 90 days in advance, and Mitel’s intention is to provide at least five years of support after that.
• After end of support (EOS), Mitel decides at its own discretion which security fixes are made.
• Extended support is available for some products, as a bridge while an upgrade is planned.

Mitel counts MX-ONE, OpenScape 4000 and OpenScape Voice among its core platforms. End-of-sale and end-of-support dates for the current versions are not public, so we find them out for your version.

The questions to ask

Factor	Question
Lifecycle	Do the version and hardware still get support and fixes?
Security	Can we get and install security fixes in time?
Licences	Is Software Assurance active, and what does it cost to reinstate?
Skills	Is the expertise available in-house and at your partner, now and in five years’ time?
Integrations	Which systems depend on the PBX: contact centre, CRM, alarms and Teams?
Hardware	Can old hardware be replaced with virtualisation?
Cost over time	What will five to seven years cost: licences, contracts, hardware, operations, operator, SBC and Teams licences?
Teams	Should Teams become the main phone, a complement, or not be used for telephony at all?
Special requirements	Analogue devices, DECT (on-site wireless phones), alarms, attendant consoles, contact centre and emergency calling?
Manufacturer	What does the future hold for the platform?
Operations and data	Must operations and data be kept in-house or in Sweden?

When upgrading often makes sense

• The platform meets your organisation’s needs, and many special extensions, such as alarms, DECT and analogue devices, work well.
• The version can be upgraded within your support coverage, and Software Assurance is active or can be reinstated at a reasonable cost.
• The integrations, such as Mitel CX or Teams via an SBC, work on the new version.
• You want control over operations and data, on your own servers or in your own data centre.

When replacing often makes sense

• The hardware is worn out and the agreement lapsed long ago, so an upgrade would in practice be a new installation.
• Telephony is moving to Teams or the cloud, and only a small part of the PBX’s functions are needed.
• Skills on the platform are disappearing, in-house or among suppliers.
• Your organisation has grown or shrunk so much that the platform is no longer the right size.

Five ways forward

• Upgrade within the platform: MX-ONE to 8.x, OpenScape 4000 and OpenScape Voice to V11, ideally while replacing your own hardware with virtualisation.
• Hybrid with Teams: the PBX keeps special functions, the contact centre and analogue devices, while users make calls in Teams via Direct Routing and an SBC.
• Move to another Mitel platform: for example from OpenScape 4000 to OpenScape Voice, where licences can be transferred within the OpenScape family.
• The cloud: MX-ONE in AWS or Azure, OpenScape Voice with a service provider, or Teams Phone with Operator Connect or Calling Plan.
• Switch to another manufacturer: the same inventory and the same migration method apply.

Start with the inventory

Whichever path you choose, the work starts by finding out what actually depends on the PBX. How we do that, and how a controlled transition works, is described under PBX migration.

Last updated 14 October 2026.