Why telephony is an IT topic again in 2026
Telephony used to be a separate topic next to IT. The phone system stood in the technical room, extensions were configured and as long as calls worked, little was questioned. Today, modern telephony depends on IP networks, firewalls, SIP trunks, internet connections, mobile devices, headsets, collaboration platforms and security concepts.
For companies, this means business telephony is part of IT infrastructure. Treating it like an old side system creates risks around outages, security and unnecessary cost.
Where Mitel stands in companies today
Mitel has been used in many companies for years. Environments are often not uniform, but grown: desk phones, DECT devices for warehouse or production, central numbers, call groups, announcements, mobile extensions and sometimes additional collaboration tools.
Common problems with grown business telephony
- Unclear call groups: central numbers ring at wrong people or old extensions.
- SIP issues: calls drop, voice quality varies or inbound and outbound calls behave differently.
- Missing documentation: extensions, numbers, devices, announcements and forwarding are not documented properly.
- Teams and telephony separated: employees chat in Teams, but calls run through another structure.
- DECT without planning: warehouse, practice, workshop or production areas have dead zones or outdated handsets.
- Security is underestimated: phone systems, gateways and management access are not treated like IT systems.
VoIP and SIP trunk: more than an ISDN replacement
Many companies have replaced ISDN, but have not rethought telephony. A SIP trunk is not just a new connection. Internet connectivity, router, firewall, quality of service, DNS, emergency routing and provider dependencies become part of telephony.
Mitel and Microsoft Teams: parallel or integrated?
Many companies use Microsoft Teams every day for chat, meetings and collaboration. At the same time, the existing phone system remains important: reception, central lines, DECT, call groups, queues, door intercoms or industry applications may still depend on existing telephony.
Hybrid telephony: useful when roles are clear
For many companies, a hybrid approach can make sense: continue using the existing phone system, modernize selected functions, improve mobile work, integrate Teams and migrate step by step instead of replacing everything at once.
Phone systems need security and updates
Telephony is now an IT system. Management interfaces, gateways, SIP access, user accounts, voicemail, remote access and integrations need protection. Phone systems must not be treated as isolated technology.
Operations: who changes what — and who documents it?
Many small changes happen in daily work: new employees, new extensions, changed call groups, announcements, home office, forwarding, headsets, DECT devices, department changes or seasonal opening hours. Without documentation, telephony loses structure every year.
Migration: do not wait until the system fails
Phone systems are often replaced only when hardware fails, support ends or a provider change creates pressure. A planned migration strategy is better. Sometimes an update, SIP concept, better documentation or step-by-step modernization is enough.
What good Mitel and VoIP consulting should deliver
1. Capture the current state
Phone system, version, extensions, SIP trunks, devices, DECT, call groups, announcements, forwarding and providers are documented clearly.
2. Understand usage
Who calls how? Which departments need call groups? Who works mobile? Where are headsets, DECT or desk phones required?
3. Review network and firewall
VoIP depends on network, internet, firewall and quality of service. Without this review, voice quality remains uncertain.
4. Assess security
Management access, SIP connectivity, updates, user accounts, passwords and provider access must be controlled.
5. Plan Teams integration or hybrid operation
Mitel and Microsoft Teams should not run side by side without a concept. A target model based on roles and working patterns is useful.
6. Create emergency and migration plans
Which numbers are critical? What happens during an internet outage? How is migration performed? Who tests it? What fallback exists?
How to identify the right telephony partner
- They ask about reachability, roles and business processes.
- They review phone system, SIP trunk, network and firewall together.
- They document numbers, extensions, groups and forwarding.
- They consider Teams, mobile work, DECT and classic devices.
- They include security, updates and emergency routing.
- They do not automatically recommend a full replacement, but the right next decision.
Conclusion: telephony is no longer a side system
Companies in Rhine-Neckar, Mannheim, Heidelberg and Ladenburg should not evaluate their Mitel phone system only by whether calls still work. The decisive question is whether telephony is secure, documented, resilient, modernizable and connected sensibly with collaboration tools.
büKOM Systemhaus GmbH supports companies with Mitel, VoIP telephony, SIP trunks, hybrid telephony, Microsoft Teams connectivity, DECT, phone system documentation, security, migration and ongoing operations.
Relevant topics: Mitel, Mitel phone system, Mitel Mannheim, Mitel Rhine-Neckar, VoIP phone system Mannheim, business telephony Mannheim, SIP trunk Mannheim, hybrid telephony, business telephony Rhine-Neckar, IT IT service provider Mannheim.