In a great many Italian companies Microsoft Teams arrived before the new telephone system. Internal chat moved there, meetings followed, and the productivity suite became the default place to work. Meanwhile the telephone stayed exactly where it was: a separate device, with its own supplier, its own number and a logic that never met the one governing everything else. The relationship between the phone system and Microsoft Teams becomes a concrete question at some point. Usually when somebody on the board observes that two systems built to let people talk do not talk to each other.
A request about the phone system and Microsoft Teams almost always lands as a binary choice: integrate or replace. In the unified communication projects run by Aesir Srl that binary choice hardly ever exists. The two routes carry different prerequisites and serve different groups of users. It pays to understand what the phone system and Microsoft Teams actually do for each other, and only then to decide.
The phone system and Microsoft Teams can be joined in two ways
The first option adds a component to the Teams side bar. Users stay in the environment they already know. To make a call they use the dial pad and the interface of the communication platform, which operates in the background. No specific Microsoft licence tier is required, so this route covers the part of the workforce that uses Teams for chat and meetings without complex telephony needs.
The second option goes deeper. Users dial from the native Teams dial pad and notice no change at all. The telephone engine underneath belongs to the communication platform, while the experience remains the Microsoft one. Prerequisites rise here, because Microsoft E3 or E5 licences are needed, plus the Phone System component. That detail moves the budget, and it has to be verified on the tenant before any evaluation rather than after it.
Both modes can be mixed within the same organisation, and this is what changes the arithmetic. Nobody has to move every user onto the most expensive tier. Part of the staff can sit on the first mode, part on the second, according to role and to licences already purchased. Technically the connection is made cloud to cloud, with no intermediate appliance to install on site. The tenant is authorised once and stays with its current Microsoft provider.
When Teams remains the home of conversations and only the engine changes
For one category of company the question of the phone system and Microsoft Teams is already answered by its own organisation. These are the businesses that invested in moving people into Teams, retired personal messaging apps and built internal communication on that foundation. In one industrial group we supported through a training programme, Teams had been declared the official tool, with presence and status aligned to the calendar. The telephone system remained a separate world, so much so that its training session had to be scheduled apart.
Displacing Teams in that situation means reopening a change that cost real effort. IT partners describe the move from consumer messaging to a corporate tool as a landmark shift for many organisations. It does not happen twice in the same three years. Telephony integration leaves those habits untouched and changes only the engine behind the calls.
When the phone system and Microsoft Teams should part ways
The balance between the phone system and Microsoft Teams shifts once conversations are no longer purely internal. A sales team or a service desk handles queues and several channels at once. It follows customers who write on WhatsApp in the morning and call in the afternoon. Teams was designed for collaboration between colleagues and does not natively provide call queues, contact history, live supervision or conversation analytics.
A car dealership with three sites described the outcome precisely: a phone system, Teams, a video conferencing platform and a customer messaging channel, none of them connected. Every tool was there. What was missing was a single place to see what had actually happened. A missed call to the workshop and an open chat with the same customer remained two unrelated events, and nobody held the full picture.
What stays and what is replaced
Replacing does not mean retiring Teams. The suite stays for meetings, documents and internal collaboration; what changes is where customer conversations live, moving onto a platform built to govern them. The previous telephony contract ends, the productivity licences stay exactly where they are. On that ground a dedicated platform adds what integration alone cannot. Automatic recording and transcription inside the conversation, summaries, sentiment analysis and natural language queries across the whole body of calls and chats. Those functions draw on dedicated processing resources rather than on the base licence, and they must be sized against real volumes. The same principle we set out when discussing knowledge bases for AI agents applies here: output quality depends on the data the system receives.
Call recording opens a chapter that is not technical. Before enabling it, privacy notices, purposes and internal policy need checking, because Article 32 of the General Data Protection Regulation requires appropriate technical and organisational measures around such processing. The platforms we integrate keep European customer data inside the European Union. Certifications come from the ISO/IEC 27001 family, with requirements aligned to NIS2, the same standards applied to our own infrastructure.
Staff away from a desk decide the phone system and Microsoft Teams question
What really settles the phone system and Microsoft Teams question is rarely the architecture. Almost always it is the population working outside the office. An engineer on site, a warehouse operator, a sales representative visiting a client: none of them opens Teams to answer a call.
Three options exist and they combine. There is the smartphone application, which carries the extension, the chat and service continuity even when site connectivity drops. There is the eSIM holding the corporate extension on a personal handset, which occupies no physical slot and exposes no private number. Cordless handsets with indoor repeaters remain the most robust answer in workshops and production areas. Devices can be purchased outright or included in the subscription, replacement covered in case of failure.
A group of three companies, three separate numbers
A group made up of three companies, roughly forty extensions in total, arrived with a clear objective. One phone system for all three, each keeping its historic number. The starting position was worse than the board believed. Cordless handsets had failed one after another and nobody had replaced them, so staff had started using personal mobiles for work. Internal communication was openly described as a problem.
At the second meeting the numbers were requested, and the picture stopped there. Nobody knew how many simultaneous outbound conversations the business could handle, because the question had never been asked. Comparing notes against the migration plan revealed the rest: two of the three companies were still completing their move to Microsoft 365. The idea of embedding telephony in Teams depended on a configuration that did not yet exist.
The decision was to wait. Evidence that it was the right call came at the following meeting, widened to other internal roles. With the tenant still in transition, any choice about integration would have rested on a temporary architecture. Operationally, that group now holds a project sequence rather than a quotation. First the migration completes, then the choice between integration and replacement, finally the porting of the three numbers under a single system.
Insight. The decision is not taken by reading datasheets. It is taken after lining up three facts. Which Microsoft licences are already owned. How many people work away from a desk. Whether the conversations to be governed are internal or customer facing.
Facts to line up before requesting a quotation
- The exact tier of Microsoft licences already purchased, tenant by tenant, and whether the telephony component is present.
- How many simultaneous outbound conversations are handled at peak, rather than the annual average.
- The split between desk users, mobile users and service devices placed in production areas or meeting rooms.
- Numbers in use per site or per company, marked as to be ported or to be retired.
- Customer facing conversation tools already active, including messaging channels run by third parties.
- Internal obligations covering recording, retention and call tracking.
- The schedule of other projects running on the tenant, since every hypothesis depends on a stable environment.
Four possible configurations, compared
| Configuration | Microsoft prerequisites | Best suited to |
|---|---|---|
| Add-on component in the Teams side bar | No specific licence tier | Office staff using Teams for chat and meetings who want the phone in the same place |
| Telephony inside the native Teams dial pad | E3 or E5 licences plus the Phone System component | Organisations standardised on Teams that will not introduce a second interface |
| Dedicated communication platform | No additional prerequisite | Sales and service teams working across channels that need queues, history and supervision |
| Artificial intelligence component only | No additional prerequisite | Companies starting with out of hours coverage while keeping the current telephone system |
Questions that arrive from the IT function
Can the artificial intelligence component be activated without changing the phone system?
Yes. A number that is not published is activated. The existing system forwards to that extension the calls it wants the automated agent to handle, passing to a human operator on request. Companies choose this arrangement to start with out of hours or missed calls, measure the result and decide afterwards. A subscription still applies: the artificial intelligence component is a service, not a device bought once.
How many simultaneous calls are included?
Simultaneous conversations depend on the licence tier assigned to the user, not on the traffic bundle. The entry tier for back office roles allows four, internal and external combined; higher tiers widen the margin alongside external collaboration features. A practical rule applied during sizing is that people do not all dial at the same instant. Across twenty or so extensions, real demand sits around four or five lines.
Does conversation data stay inside Europe?
Communication platforms we integrate keep European customer data within the European Union, separating the application layer from the data layer and encrypting traffic. Audio, video, chat and documents are encrypted by default, including towards external participants. Specific treatment of recordings and transcripts should be checked with the company data protection officer, since it depends on the purposes and notices adopted.
Is it possible to keep Teams now and change the phone system later?
That sequence is both the most frequent and the most sensible while the Microsoft tenant is still moving. Stabilise the productivity environment first, then pick the integration mode on the basis of licences actually in use. Deciding earlier means sizing against an architecture that will change within months.
How are multiple sites or companies brought under one system?
Porting of existing numbers is required, together with a numbering structure that keeps each site identifiable. Instances can be networked together, share user licences and resynchronise when connectivity returns; where the line is fragile, a local appliance lets handsets keep communicating. Companies weighing a change of supplier will find the criteria for what survives a transition in our article on changing CRM partner.
Let’s talk
An assessment of the phone system and Microsoft Teams closes well when the company reaches its decision holding three elements. The licence map, the real profile of its users, the nature of the conversations to be governed. Without them every configuration looks plausible, and the exercise collapses into a comparison of monthly fees that says nothing about the operating result.
The rule we apply is simple: where the conversations to govern are internal, telephony is integrated into Teams. Where they involve customers and arrive across several channels, the conversation moves to a dedicated platform and Teams keeps the internal work. Aesir runs unified communication projects across Italy under the same contractual perimeter it uses for infrastructure and security. Integration with the business software in use is achieved through available connectors or built to order. If you would like to explore the subject or assess the situation in your own company, you can fill in the form at the bottom of this page or write to support@aesir-tech.it: we will arrange a free consultation and start from your numbers.