If employees working from home can only be reached via Teams, but calls to the main number still go to a separate desk phone, this creates unnecessary detours. Microsoft Teams with Landline Calling brings both together on a single platform: internal communication, external business calls, and the features of a professional phone system.
For Swiss SMEs, this is more than just a matter of convenience. They keep their existing phone number, customers can still reach them at the familiar main number, and employees can make calls regardless of their workstation or location. However, it’s not just a matter of whether Teams rings. What matters is how phone numbers, reachability rules, security, and existing processes are seamlessly integrated.
What Microsoft Teams Means for Landline Telephony
Microsoft Teams is primarily a collaboration platform for chat, meetings, and file sharing. To enable external calls over the public telephone network, Teams requires a connection to traditional landline telephony. This connection is established through a telephony provider and a suitable routing architecture, such as a SIP trunk and a Session Border Controller (SBC).
For users, it’s simple: They choose a Swiss landline number in Teams, answer incoming calls in the Teams client, or use an IP phone if needed. Behind the scenes, the phone system determines which number is displayed, where a call rings, and which rules apply for business hours, groups, or call forwarding.
This does not necessarily mean that Teams itself becomes a full-fledged PBX. Depending on the requirements, Teams either supplements the existing phone system or connects directly to a cloud PBX. This distinction is particularly relevant for companies with a reception desk, multiple departments, or complex call groups.
The Benefits in Day-to-Day Business Operations
The most obvious benefit is accessibility. An employee can work in the office, from home, or on the go and remain reachable at their business number. The call follows the person rather than a specific device. This reduces missed calls and makes hybrid work arrangements invisible to customers.
Equally important is a consistent user experience. Employees don’t have to switch between softphones, cell phones, and Teams to make calls or search for contacts. Presence information helps them reach specific colleagues. A call can be forwarded, placed in a queue, or transferred to the appropriate specialist for consultation.
From an IT perspective, a centrally managed solution simplifies administration. New employees are assigned their phone number, access permissions, and telephony settings according to clear rules. In the event of growth, seasonal teams, or new locations, capacity can be adjusted without having to reconfigure a traditional system at every workstation. Predictable flat rates or per-minute rates provide additional transparency regarding ongoing costs.
Which phone features Teams does not automatically handle on its own
For simple direct extensions, a Teams integration may be sufficient. In many companies, however, professional telephony begins before the first call: The caller hears a greeting, selects a department, is placed in a queue, and is transferred according to defined rules if the call is not answered. These PBX functions must reliably align with the organization’s needs.
These include, for example, IVR menus, time-controlled announcements, call routing to executives and secretaries, group calls, pick-up groups, busy light panels, and detailed call forwarding rules. Displaying the company’s main number instead of a personal extension is also often essential for sales, customer service, or reception.
Anyone using CRM or ERP systems should also consider CTI features. Clicking on a phone number, displaying the caller’s information when the phone rings, or logging calls can significantly speed up workflows. However, such integrations depend on the PBX in use, the CRM system, and the desired processes. A one-size-fits-all Teams solution is no substitute for a thorough requirements analysis.
The Right Architecture: Teams, SIP Trunk, and PBX
In practice, there are several ways to integrate Microsoft Teams with landline telephony. The best approach depends on the existing infrastructure, the features, and the security requirements.
With Direct Routing, an SBC connects Teams to a SIP trunk or a phone system. This model offers a great deal of flexibility, for example, when dealing with existing blocks of phone numbers, multiple locations, or specific routing rules. The SBC serves as a central security and switching hub between the Microsoft environment and the telephone network. It should be professionally operated, monitored, and kept up to date.
A cloud PBX with native Teams integration is often the most practical solution for small and medium-sized businesses. The phone system functions remain within the PBX, while Teams becomes the familiar interface for employees. With Winet, the Ayrix PBX can be integrated directly with Connect to Microsoft Teams, without separate Teams add-ons or SBC components that require a license. This can reduce complexity and ongoing costs, provided that this model covers the required features.
For individual workstations or highly standardized requirements, more preconfigured telephony solutions may also be suitable. They can often be implemented more quickly, but offer less flexibility when it comes to custom routing logic, integrations, or international numbers. If you operate multiple locations, a service team, or established telephony processes, you’re usually better off with a flexibly configurable PBX.
Port Your Phone Numbers and Stay Professionally Reachable
The main number is part of the company’s identity. Therefore, there is no need to give it up when switching to Teams telephony. Existing Swiss landline numbers and extension blocks can generally be ported. It is important to have complete documentation, the correct contract holder, and a realistic timeline.
The migration should not take place until routing, end devices, and user permissions have been tested. A clear procedure is needed during the transition: Who can be reached if there are any questions? Which call groups will be activated first? How will emergency numbers and external call forwarding be verified? Scheduling the switch outside of critical business hours minimizes risks.
New phone numbers can also be used for specific purposes, such as new locations, campaigns, or international markets. In this context, it’s worth having a clear numbering strategy. A central main number builds brand recognition, while extensions and function numbers simplify internal assignment.
Security and voice quality are part of the planning process
Making calls via Teams depends on a stable internet connection. The requirements for a single person working from home differ from those for an office with 50 people making calls simultaneously. Bandwidth alone is not enough. Latency, packet loss, Wi-Fi coverage, and the prioritization of voice data directly affect whether calls remain clear and intelligible.
A business Internet connection with a properly configured network is therefore part of the telephony solution. Quality of Service can prioritize voice traffic, a firewall protects network gateways, and site-to-site networking ensures that multiple offices operate according to uniform rules. In demanding environments, reliability should also be assessed, for example through redundant Internet connections or defined rerouting in the event of disruptions.
Data protection and access control deserve equal attention. Administrators need clearly defined roles, changes to call forwarding should be traceable, and external interfaces must be secured. A managed SBC or managed service can be a useful solution here if there are no internal resources available for operation, monitoring, and updates.
How to Ensure a Smooth Rollout Without Disrupting Phone Service
A good onboarding process doesn't start with licenses, but with the call plan. What numbers are available? Which teams handle calls? What are the business hours, on-call schedules, or special rules? Only then is it determined which functions should be handled by Teams, the PBX, or a specialized application.
Afterward, it’s a good idea to conduct a pilot with a manageable group of users. This will bring to light questions that are often overlooked on paper: Should the desk phone ring at the same time? What number is displayed for external calls? Does the call transfer to reception work? How do employees react to headsets and Teams presence status?
Training sessions don't have to be long, but they should be practical. Three real-world scenarios are often enough: calling a customer, transferring a call, and setting your own availability correctly. For administrators, there also needs to be a documented assignment of responsibilities for numbers, groups, and changes. This ensures that the solution remains manageable even after the project is complete.
Microsoft Teams with landline telephony works best when technology and accessibility are planned together. By first organizing your call routes effectively, you’ll not only create a modern telephony interface but also a communication structure that can grow with your business.
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