Telstra Calling for Office 365 (TCO365) is being withdrawn. Telstra has advised the service will no longer be provided from 30 November 2026. If your organisation makes and receives calls through Teams using TCO365, you need a replacement in place before that date - and the window to plan a considered move is closing.
The good news: this is a change to how your calls reach the phone network, not a change to Microsoft Teams. Handled properly, your people keep the same numbers, the same Teams experience, and the same way of working. Here’s what’s happening, what it means, and how to move.
Is Telstra Calling for Office 365 ending?
Yes. TCO365 closed to new customers on 1 November 2024. Existing customers have been unable to add, change, or recontract services since 30 August 2026, and Telstra has stated the service will be withdrawn on 30 November 2026 unless it advises otherwise.
That means the service most organisations have relied on to connect Microsoft Teams to the public phone network is in its final weeks. If you haven’t started planning your migration, now is the time.
Key TCO365 retirement dates
| Milestone |
Date |
| Closed to new customers |
1 November 2024 |
| No new services, changes, or recontracts |
30 August 2026 |
| Service withdrawn |
30 November 2026 |
Dates are as published by Telstra at the time of writing.
Note what the August milestone means in practice: even if your service is running fine today, you can no longer add users, change plans, or adjust the service. Your TCO365 environment is frozen exactly as it is until it’s switched off.
What the withdrawal means for your Teams calling
It’s worth being clear about what is and isn’t affected.
Microsoft Teams is not going anywhere. Your chat, meetings, files, and collaboration continue exactly as they are. Teams Phone - Microsoft’s calling platform inside Teams - also continues and keeps improving.
What’s being retired is the carriage. TCO365 was the link between Teams and the Australian phone network. When it’s withdrawn, calls to and from the outside world stop working unless a new connection is in place.
So the task isn’t replacing your phone system. It’s replacing one layer underneath it – the part that carries your calls. That’s a much smaller project than most people fear, but it still needs lead time for number porting, call flow configuration, and testing.
Your migration options after TCO365
Operator Connect - the modern path for Teams Phone
Operator Connect is Microsoft’s current framework for connecting Teams Phone to a carrier. Your numbers and calling plans appear directly in the Teams admin centre, provisioning is handled through the platform rather than through tickets, and the carrier relationship is certified by Microsoft.
For most organisations leaving TCO365, this is the natural destination. You keep the Teams-native experience you chose TCO365 for in the first place, with a provider whose whole business is Teams calling - not a product line at the edge of a large carrier’s portfolio.
Direct Routing
Direct Routing connects Teams to a carrier through session border controllers. It offers flexibility - useful if you have complex requirements like contact centre integration, analogue devices, or unusual number arrangements. It carries more configuration to own, so it suits organisations with specific needs rather than being the default.
Another carrier-led bundle
You can move to another large carrier’s packaged Teams calling product. Before you do, ask the question this retirement has already answered once: what happens when a carrier decides the product no longer fits its portfolio? Choosing a specialist whose core business is Teams calling removes that risk.
Can you keep your phone numbers?
Almost always, yes. Australian numbers are portable between providers under the national numbering rules. Your new provider lodges a porting request, and your numbers - including 1300 and 1800 ranges - move across.
Two things to plan for: porting has lead times, and complex ranges across multiple sites may need to be staged rather than moved in one cutover. This is the single best reason not to leave your migration until November. Porting queues will only get busier as the deadline approaches and every remaining TCO365 customer moves at once.
How long does a migration actually take?
For a single site with straightforward call flows, a Teams calling migration is typically measured in weeks, driven mostly by porting lead times. For organisations with multiple sites, auto attendants, call queues, and integrations, allow a few months for discovery, staged porting, and testing.
How Switch Connect migrates Teams calling
Switch Connect is an Australian-owned Microsoft technology and telecommunications provider. We support more than 400 organisations with voice coverage across 65+ countries, and Microsoft Teams calling through Operator Connect is core to what we do - not an add-on.
Our migrations follow a structured path: we map your current environment (users, numbers, call flows, devices), design the target Teams Phone setup, stage the number porting so nothing is cut over untested, and validate every call flow before the old service is switched off. You’re supported by Australian-based engineers throughout.
We’ve done this at scale. Only About Children moved around 700 handsets across 80 campuses to Microsoft Teams Phone with Operator Connect - you can read the full story in our recent case study.
Where to start
The first step isn’t choosing a provider - it’s understanding what you’re actually running today. Most TCO365 environments have grown over years, and undocumented call flows are the number one cause of migration surprises.
Our Teams Calling Health Check gives you exactly that: a structured review of your current Teams calling environment, your numbers and call flows, and a clear migration path with realistic timelines - whether or not you migrate with us.
Frequently asked questions
Is TCO365 being discontinued?
Yes. Telstra has advised that Telstra Calling for Office 365 will be withdrawn on 30 November 2026, unless it advises otherwise. The service has been closed to new customers since 1 November 2024.
When does Telstra Calling for Office 365 end?
The published withdrawal date is 30 November 2026. Existing customers have been unable to add, change, or recontract services since 30 August 2026.
Do I have to stop using Microsoft Teams?
No. Teams and Teams Phone continue as normal. Only the connection between Teams and the phone network is being retired, and it can be replaced with an alternative such as Operator Connect.
Will I lose my phone numbers?
In nearly all cases, no. Australian numbers are portable, and your new provider manages the porting process. Allow for porting lead times, especially for complex or multi-site number ranges.
What replaces TCO365?
The main options are Operator Connect (the modern, Microsoft-certified path for Teams Phone), Direct Routing (for complex requirements), or another carrier’s packaged product. For most organisations, Operator Connect is the natural fit.
How long does migration take?
Simple single-site environments typically take weeks; multi-site environments with complex call flows can take a few months. Starting now leaves room for a staged, low-risk cutover before the deadline.
Book a Teams Calling Health Check Today.