Why VoIP phone systems need more support in 2026
Telephony used to be separate from IT. Today, it often runs through IP networks, SIP trunks, virtual phone systems, cloud services, Microsoft Teams, softphones, headsets and mobile apps. This makes telephony more flexible, but also more dependent on network, firewall, internet and clean configuration.
Current topics: Teams telephony, SIP and emergency calls
Microsoft Direct Routing connects a customer-provided Session Border Controller with Microsoft Teams Phone. This allows companies to integrate Teams into existing telephony and SIP trunk environments, but it requires planning for SBC, certificates, firewall, SIP provider, numbers, emergency calls, network quality and support.
Common VoIP and phone system problems
- Choppy calls: packet loss, latency, jitter or overloaded connections affect voice quality.
- One-way audio: firewall, NAT or SIP ALG problems prevent clean media flow.
- Unclear call groups: forwarding, groups, announcements and busy rules have grown over time.
- Old devices: desk phones, DECT systems or headsets no longer fit the modern VoIP environment.
- Missing emergency strategy: it is unclear how reachability continues during internet or power outages.
- No documentation: numbers, extensions, SIP access, provider data, routing rules and passwords are not documented.
What good VoIP support should deliver
1. Inventory and number concept
Numbers, extensions, groups, queues, announcements and forwarding rules should be transparent and documented.
2. SIP trunk and provider connection
SIP trunks connect the phone system to the public phone network. Authentication, numbers, routing, codecs, emergency calls, firewall, redundancy and provider requirements must fit.
3. Network quality for voice
VoIP needs stable packet delivery. Switches, VLANs, prioritization, internet access, firewall and Wi-Fi must be coordinated.
4. Firewall and security
Telephony should not be exposed to the internet without control. Firewall rules, SIP access, management ports, updates, passwords, certificates and logs must be reviewed regularly.
5. Devices, DECT and softphones
Desk phones, DECT base stations, headsets, softphones, mobile apps and Teams clients must match daily work.
6. Documentation and support
Number plans, extensions, groups, provider data, SIP access, devices, licenses, emergency paths and administrator access should be documented.
Mitel phone system support: continue existing systems sensibly
Many companies use existing Mitel phone systems and do not want to replace everything too quickly. This can make sense when the system, devices, licenses, maintenance, security and future viability are reviewed regularly.
Teams telephony: when Microsoft Teams becomes the phone system
Many companies already use Microsoft Teams for meetings, chat and collaboration. The next step is often telephony through Teams Phone. Direct Routing or operator models need planning for number porting, emergency calls, SBC, firewall, licensing, devices, reception functions, queues, legacy fax requirements, DECT needs and outage concepts.
Emergency calls and location: especially important with VoIP
VoIP makes telephony more flexible, but also more complex. When employees call from different sites, home office or mobile devices, companies must know which number and location are relevant for emergency calls.
Resilience: what happens if internet or power fails?
VoIP depends on internet, network, switches, firewall, power supply and provider availability. Companies need a fallback concept for internet outages, forwarding to mobile numbers, backup connections, cellular fallback, UPS or cloud routing.
Telephony security: protect against misuse and cost traps
Phone systems can be targeted for misuse. Attackers may try to initiate expensive international calls, abuse SIP access or take over administrator accounts. Strong passwords, updates, access restrictions, log review and clean firewall rules are therefore part of phone system support.
Common VoIP phone system mistakes
- Telephony is migrated without reviewing network, firewall and internet access.
- SIP credentials and provider information are not documented.
- Call groups and forwarding rules grow for years without cleanup.
- Emergency calls and location data are checked too late or not at all.
- There is no fallback concept for internet, power or provider outages.
- Phone system, Microsoft 365, Teams and IT support are handled separately.
How companies recognize good phone system support
- Numbers, extensions, groups, announcements and routing are documented.
- Network, firewall, SIP trunk and phone system are considered together.
- Emergency calls, location data and mobile usage are reviewed.
- There is a clear outage and forwarding concept.
- Devices, softphones, DECT, headsets and Teams fit daily work.
- Updates, security, logs and provider requirements are supported regularly.
Conclusion: modern telephony needs IT competence
VoIP phone systems offer more flexibility, better integration and modern work options. At the same time, requirements for network, security, emergency calls, documentation, resilience and ongoing support increase.
büKOM Systemhaus GmbH supports companies in Rhine-Neckar, Ladenburg, Mannheim and Heidelberg with VoIP phone systems, Mitel phone system support, SIP trunks, Teams telephony, phone system support, network quality, firewall integration, emergency call concepts, resilience and ongoing IT support.
Relevant topics: phone system for companies, VoIP phone system, Mitel phone system support, SIP trunk, phone system support, Teams telephony, business phone system, büKOM Systemhaus GmbH.