This practical guide explains how UK organisations can deploy Microsoft Teams Calling with Direct Routing or Operator Connect, integrate SIP trunks via an SBC (Session Border Controller), complete number porting with zero downtime, and deliver reliable VoIP quality using QoS (Quality of Service). We cover DID mapping, auto-attendant, call queues, voicemail-to-email, and the device strategy (headsets, IP phones, softphones) that fits a modern hybrid office.
Key takeaways
- Direct Routing with certified SBCs connects Teams to the PSTN using resilient SIP trunks.
- Staged number porting with diverts ensures a zero-downtime VoIP migration.
- DID mapping, auto-attendant & call queues streamline call flows for sales, support and reception.
- QoS for VoIP/Teams: DSCP tagging, WAN queueing and guest network shaping prevent choppy calls.
- User adoption: certified headsets, softphones, quickstart guides and short training sessions.
Direct Routing vs Operator Connect: which is right?
Direct Routing gives full control with a certified SBC and your choice of carrier SIP trunks, ideal for multi-site and advanced routing. Operator Connect simplifies carrier integration but offers less customisation. We’ll recommend the best fit based on compliance, recording, budget and resilience requirements.
Number porting & zero-downtime migration
We audit all DIDs, hunt groups and diverts, then schedule staged ports with out-of-hours windows. Temporary call diverts keep inbound calls reaching your users during cutover; we validate ranges in real time and hold a clear rollback plan. Users receive voicemail-to-email and new Teams softphone profiles in advance, so the change feels seamless.
DID mapping, auto-attendant & call queues
We build a simple, SEO-friendly call architecture: auto-attendant (IVR) for departments, time-based routing for bank holidays, call queues for support desks, and overflow rules to duty mobiles. Reception gets a dashboard/wallboard for visibility, while managers see analytics on answer rates and wait times.
Devices & user adoption
Most UK office deployments pair certified Teams headsets with softphones; reception may use a Teams-certified phone or sidecar. We provide quickstart guides, role-based training and a short “day-one” checklist. For remote staff, we enable MFA and secure profiles with Intune/MDM.
QoS: how to keep Microsoft Teams & VoIP crystal-clear
- DSCP tagging for RTP media (EF) and Teams signalling; preserve tags across switches and routers.
- WAN queueing & shaping to prioritise voice/video; guest Wi-Fi rate-limits and VLAN isolation.
- Proactive monitoring & alerts for jitter, packet loss and MOS.
Where uptime is critical, consider Leased Lines with SLAs; otherwise FTTP or SOGEA can be excellent value with the right firewall & security.
Compliance, recording & retention
We enable compliant call recording (where required), role-based access, and sensible retention policies. If you need PCI controls, we segment devices and apply least-privilege to minimise exposure.
Rollout plan & timelines
- Discovery: inventory numbers, queues, IVRs, sites, and carriers.
- Build: SBC/Direct Routing, policies, DID mapping, auto-attendant, call queues.
- Pilot: a small department proves call flows and quality.
- Stage ports: waves by department/site with temporary diverts and out-of-hours windows.
- Adoption: headset rollout, quickstarts, training; wallboards and analytics.
Related guides
FAQs
Can we keep our existing geographic numbers (DDIs)?
Yes. We port DDIs in waves and keep temporary diverts so no inbound calls are lost during migration.
Do we need new desk phones?
Not necessarily. Many offices go softphone-first with certified headsets. Reception can use a Teams-certified IP phone if preferred.
How do you ensure call quality?
End-to-end QoS with DSCP, WAN queueing, guest shaping, and proactive monitoring. For critical sites, consider a Leased Line.