Microsoft Teams is already the go-to platform for chats, meetings, and collaboration in many companies. With this guide to Microsoft Teams telephony, it also becomes a professional telephony solution: Employees can make calls using their business number and can be reached in the office, while working from home, and on the go. What matters isn’t just whether a call works technically. A good solution must effectively integrate phone numbers, availability rules, security, existing processes, and costs.
What Microsoft Teams Telephony Must Be Able to Do
Teams alone does not replace a full-fledged corporate phone system. To make calls to the public telephone network, you need a connection to a telecommunications provider as well as the appropriate Microsoft licenses. Only then can employees call external numbers and be reached at a Swiss or international business number.
For small teams, one direct extension per person is sometimes enough. In an SME In an organization with multiple departments, the requirements are usually more extensive: a central main number, an automated greeting, business hours, call groups, call forwarding, queues, call transfers, and call analytics are all part of everyday operations. Fax machines, intercom systems, conference rooms, analog devices, and a CRM system may also continue to play a role.
This is exactly where the difference between a simple Teams integration and a well-designed communication architecture becomes apparent. Teams serves as the user interface for many employees. The phone system and the trunk in the background, on the other hand, control how calls are routed, prioritized, logged, and secured.
Choose the Right Connection Method
There are three common models for connecting Teams to the public telephone network. Which one is right depends on the existing infrastructure, the desired flexibility, and the range of features.
Microsoft Calling Plans
With Calling Plans, the telephony service comes directly from Microsoft. The model is easy to set up and may be suitable for clearly defined use cases. In Switzerland, however, and when international phone numbers are needed, companies should carefully check which numbers, countries, rates, and additional features are actually available. Those who need complex PBX scenarios or custom routing rules may quickly reach their limits, depending on their requirements.
Operator Connect
Operator Connect connects Teams to a Microsoft-approved carrier. Provisioning is largely handled in the Teams Admin Center, which can simplify administration. This is an attractive option for companies seeking standardized Teams telephony, provided the chosen provider covers all the necessary phone numbers, locations, and features.
The advantage lies in the ease of implementation. The downside: Specific requirements—such as multi-level IVR menus, integration with an existing phone system, customized emergency call protocols, or special routing logic—must be addressed early on. A standardized solution is not automatically the right fit.
Direct Routing with SIP Trunk and PBX
With direct routing, Teams is connected via a session border controller (SBC) to a SIP trunk and, if needed, to a cloud-based or on-premises phone system. This model offers a great deal of flexibility. Existing phone numbers can be ported, locations can be connected in a uniform manner, and PBX functions can be continued or expanded as needed.
For companies with multiple locations, reception groups, contact center requirements, CRM integration, or a mix of end devices, direct routing is often the more cost-effective and sustainable option. However, it requires a well-planned architecture. SBCs, network quality, security policies, and responsibilities must not be addressed only after the go-live.
Identify Requirements Before Migration
The most common problems with Teams telephony aren’t caused by the software, but by incomplete requirements. If you only count the number of users, you’ll overlook the operational aspects of telephony. It makes sense to map out your current call routes: What are the main numbers? Who answers incoming calls? What happens outside of business hours? Which teams or individuals need direct extensions?
Special cases are just as important. These include emergency numbers and accurate location mapping, alarm or elevator phones, DECT devices, door intercoms, fax services, and shared areas such as the reception desk or conference rooms. Interfaces with CRM, ERP, or contact center solutions should also be documented. CTI integration is only beneficial if responsibilities, data quality, and workflows are aligned with it.
For distributed organizations, it’s worth taking a look at the network architecture. Work-from-home stations, mobile employees, and remote offices do not need identical technical equipment, but they do require a consistent policy for availability and security. Business phone numbers should not have to be redirected to personal cell phone numbers simply because an employee is not at their desk.
Organizing Phone Numbers, Availability, and the PBX Properly
For customers, a phone number is part of a company’s identity. A migration should therefore retain existing main numbers and extensions whenever possible. Number porting takes time and requires the correct documentation. Parallel operation, clear deadlines, and a tested contingency plan ensure that customers do not end up calling a dead line during the transition.
The responsibility for managing call handling lies with the line departments, not exclusively with IT. Sales may require different rules than Support, and the reception desk may have different rules than the on-call service. Teams call queues can handle a wide range of scenarios. A PBX complements these systems in cases where, for example, complex IVR menus, time-based routing, overflow destinations, group permissions, or comprehensive statistics are required.
Here’s an example: Calls to the main number are initially routed to the front desk during business hours. If no one answers there, they are forwarded to a designated group. Outside of business hours, an automated message provides information about the next business day or forwards urgent inquiries to the on-call service. Such rules should be easy for customers to understand and simple for administrators to customize.
Security and voice quality go hand in hand
Telephony via Teams is a service that relies on the Internet, identities, and networks. That’s why good headsets and a fast connection alone aren’t enough. Voice quality depends on stable bandwidth, low latency, proper prioritization, and a correctly configured network. When connections are heavily loaded, Quality of Service can be critical.
On the security front, multi-factor authentication, clearly defined roles in the Teams Admin Center, and a structured approach to managing user accounts form the foundation. The SBC protects the boundary between the corporate network and the telecommunications provider when Direct Routing is used. Firewall rules, certificates, logging, and updates must be managed on an ongoing basis, not just during implementation.
Data protection also deserves attention. Call recordings, voicemail, and call data may contain personal or business-critical information. Companies should define who is authorized to access this information, how long data is stored, and what guidelines apply to recordings. Technical measures are no substitute for clear internal rules.
Plan Licenses and Costs Transparently
The cost of Teams calling involves more than just the per-minute rate. You must also factor in Microsoft licenses for the calling feature, SIP Trunks or Connection Fees, phone numbers, any flat-rate plans, PBX licenses, hardware, implementation, and managed services. Depending on the plan, international calls, calls to mobile numbers, or special numbers may also be billed separately.
A flat rate makes budgeting easier, but it isn’t automatically the most cost-effective option for every usage profile. Companies with few external calls may be better off with per-minute billing. For teams that make a lot of calls, service organizations, or international locations, however, a detailed review of rate plans is worthwhile. The key is to ensure that costs remain transparent per user, location, and usage scenario.
When it comes to technical architecture, the purchase price shouldn’t be the only factor. A seemingly inexpensive standalone solution can end up being costly if multiple service providers are responsible for each customization. An integrated PBX and Teams connection reduces the number of interfaces and simplifies operations. At Winet, the Ayrix PBX integrates natively with Microsoft Teams integrate, so that in many scenarios, a separate SBC component on the customer side—which would require a license—is not necessary.
Introduction in Controlled Steps
A pilot involving a manageable group of users will quickly reveal whether phone number assignment, headsets, call rules, and network quality work in everyday use. The pilot should not be limited to IT staff. Reception, sales, support, and management can test the features from different perspectives and provide relevant feedback.
This is followed by the phased migration. Users need a brief, practical introduction: How do I make external calls? How do I change call forwarding settings? Where can I access voicemail? How does the business number work on my mobile device? Positive user acceptance isn’t achieved through lengthy manuals, but through clear settings and accessible support on the first day of work.
After the go-live, it’s worth establishing an operational phase with designated points of contact and measurable metrics. These include dropped calls, wait times in queues, voice quality reports, and recurring support questions. This transforms a technical transition into a telephony solution that truly simplifies day-to-day work.
Anyone who wants to use Teams as their primary telephony channel should first map out the actual call routes and business processes. Based on this, phone numbers, PBX features, security, and rate plans can be combined in a way that ensures employees remain reachable while keeping administrative tasks manageable.
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