Microsoft Teams has become the default collaboration platform for South African enterprises, but turning it into a full telephone system — with PSTN calling, phone numbers, call queues, and auto-attendants — requires a voice integration strategy. For communications service providers and telecoms resellers, the choice between Calling Plans, Operator Connect, and Direct Routing determines not only the technical architecture but also the commercial model, the margin structure, and the long-term customer relationship.
This guide explains how each option works, maps them to the South African market, and provides a practical framework for resellers building a Teams voice practice.
Three Paths to Teams Voice: Understanding the Options
Microsoft offers three routes for connecting Teams to the public telephone network, each with fundamentally different ownership models.
Microsoft Calling Plans place Microsoft in the role of telephone carrier. The customer buys phone numbers and call minutes directly from Microsoft alongside the Teams Phone licence. Setup is simple — no hardware, no SBC, no carrier relationship to manage. But Calling Plans are available in only around 33 countries, and South Africa is not among them. For SA resellers, this option is off the table entirely, though it is useful to understand when advising multinational customers with offices in supported markets.
Operator Connect positions a licensed carrier as the intermediary. The carrier manages the SBC infrastructure and provides phone numbers, while the customer provisions services through the Teams Admin Centre. In South Africa, Liquid Intelligent Technologies offers OneVoice for Operator Connect — a cloud-native service that requires no on-premise hardware and integrates directly with Teams. Operator Connect is the simplest viable option for SA organisations that want Teams voice without managing telephony infrastructure.
Direct Routing gives the customer — or their reseller — full control. The organisation deploys a certified Session Border Controller, connects it to a SIP trunk from a local carrier, and configures voice routing policies in Teams. Direct Routing offers maximum flexibility: any carrier, any SBC, any call flow. It also carries the highest complexity and the greatest opportunity for a reseller to build a managed service practice around ongoing support, monitoring, and optimisation.
How Direct Routing Works: The Technical Architecture
At its core, Direct Routing places a certified SBC between Microsoft’s Teams cloud infrastructure and the public telephone network. The SBC performs three essential functions: it secures signalling traffic using TLS encryption, it manages media streams using SRTP, and it translates between the SIP protocols used by Teams and the SIP dialect spoken by the local carrier’s network.
The call flow for an outbound call runs as follows. A Teams user initiates a call, and Teams routes the SIP signalling to the configured SBC via Microsoft’s SIP proxy. The SBC validates the request, applies any configured routing rules (least-cost routing, geographic routing, time-of-day rules), and forwards the SIP INVITE to the carrier’s SIP trunk. The carrier completes the call to the destination number on the PSTN. Media — the actual voice audio — can flow directly between the Teams client and the SBC (media bypass) or route through Microsoft’s media processors, depending on the network topology.
The SBC must be Microsoft-certified. The three vendors most commonly deployed in the South African market are AudioCodes, Ribbon Communications, and Patton. AudioCodes’ Mediant family holds the number-one global position for enterprise SBCs and offers extensive Teams Direct Routing documentation. Ribbon’s SBC SWe and SBC Edge range covers enterprise through carrier-scale deployments with 99.999 per cent uptime capability. Patton’s SmartNode series targets the SME segment, combining SBC functionality with enterprise routing in a single compact appliance — a practical choice for smaller deployments where a dedicated SBC appliance would be overkill.
Call2Teams: The Middleware Alternative
For resellers who recognise the commercial opportunity in Teams voice but lack the appetite to manage SBC infrastructure, Dstny’s Call2Teams middleware offers a compelling middle path. Call2Teams is a cloud-native platform that sits between the existing telephony layer and Microsoft 365 tenants, abstracting the complexity of SBC management into a managed service.
In South Africa, Telviva operates as the primary Call2Teams partner, having launched the country’s first SaaS solution for native Teams voice integration. Telviva’s Call2Teams service processed 445 million calls in 2025 and claims cost savings of up to 40 per cent compared with Microsoft Teams Phone alone and up to 25 per cent cheaper than traditional Direct Routing deployments.
The trade-off is control. Direct Routing with a customer-managed SBC offers unlimited customisation of call flows, codec selection, and failover behaviour. Call2Teams abstracts these decisions into the platform, which suits the majority of deployments but may constrain organisations with highly specific telephony requirements.
SA-Specific Providers and Their Approaches
The South African market offers several distinct routes to Teams voice, each suited to different customer profiles.
Telviva’s Call2Teams service targets organisations that want Teams voice without telephony infrastructure management. Call2Teams is designed for customers with Teams Phone licences. Telviva’s offering covers a broad range of SA customer profiles. The company’s 95,000-user base and CEM Africa contact centre awards provide credibility in the enterprise segment.
Liquid Intelligent Technologies’ OneVoice for Operator Connect provides a carrier-grade option for larger enterprises and government organisations. As an Operator Connect partner, Liquid manages the full SBC and PSTN stack, and customers provision Teams voice directly through the Microsoft Teams Admin Centre. Coverage extends across South Africa and into Zimbabwe, Zambia, Kenya, Uganda, and Rwanda — valuable for organisations with pan-African operations.
ECN — the Reunert-owned carrier that was the first new entrant to achieve bilateral interconnection with all SA incumbent networks — offers carrier-grade SIP trunking suitable for Direct Routing deployments. ECN’s SIP trunks connect to Telkom, MTN, Vodacom, and Cell C directly, providing clean call routing and competitive per-minute rates for organisations that choose to manage their own SBC.
United Telecoms offers a SIP2Teams module that converts Teams into a functional PSTN platform, enabling Teams desktop and mobile extensions to dial local SA numbers via SIP trunking.
POPIA Compliance: The Non-Negotiable Requirement
Any Teams voice deployment in South Africa must address call recording compliance under the Protection of Personal Information Act. POPIA requires explicit consent before recording calls, secure encrypted storage of recordings (AES-256 minimum), access controls limiting who can retrieve recordings, defined retention periods with automatic deletion, and mechanisms for data subjects to access or request deletion of their recordings.
Microsoft Teams’ built-in recording feature does not meet POPIA compliance requirements. It lacks granular consent management, offers limited control over storage location, and does not provide the automated retention enforcement that POPIA demands. Resellers should always recommend a third-party compliance recording solution as part of any Teams voice deployment.
CallCabinet’s Atmos platform offers POPIA-compliant recording with South African data residency, quality assurance tools, and AI-powered analytics specifically designed for the Teams environment. Resellers who bundle compliance recording into their Teams voice offering create a recurring revenue stream while ensuring customers meet their regulatory obligations from day one.
Cost Comparison: What SA Resellers Should Quote
Teams Phone licensing costs $10 per user per month as of April 2025 — a prerequisite for all three voice options. Beyond the licence, costs diverge significantly.
Operator Connect through Liquid OneVoice adds approximately $6 to $12 per user per month depending on calling volumes. For a 100-user organisation, the total annual cost sits around $21,600 — roughly $216 per user per year with no hardware investment.
Direct Routing via Call2Teams through Telviva adds approximately $6 per user per month for the middleware service. With minimal or no SBC infrastructure costs (middleware is cloud-based), the total annual cost for 100 users drops to approximately $19,700 — the most cost-effective option at the SMB scale.
Direct Routing with a fully customer-managed SBC involves SIP trunking costs (variable by carrier, typically $6 to $10 per user per month), SBC hardware or virtual appliance costs (amortised at $3,000 to $8,000 per year), and ongoing SBC management and support ($2,000 to $5,000 per year). The total annual cost for 100 users ranges from $26,600 to $34,600 — higher upfront but potentially the lowest per-user cost at enterprise scale above 500 users where the fixed SBC costs are amortised across a larger base.
Common Pitfalls Resellers Should Avoid
SBC pairing failures are the most common deployment issue. Mismatched FQDNs between the Teams Admin Centre configuration and the SBC, expired or incorrectly installed TLS certificates, and firewall rules blocking SIP port 5061 or the RTP media port range (50000 to 51000) account for the majority of failed Direct Routing setups. A pre-deployment checklist covering FQDN alignment, certificate validity, and firewall rules eliminates most first-day issues.
Over-centralised architecture — deploying a single SBC for an entire enterprise — creates a single point of failure and can introduce latency for remote offices. Distributed SBC deployments with regional failover, or the use of media bypass to route audio directly between the Teams client and the local network, improve both resilience and call quality.
Positioning Teams voice as a commodity rather than a managed service is the commercial pitfall. Resellers who sell Direct Routing as a low-cost voice pipe compete on price and lose margin. Resellers who bundle monitoring, SLA guarantees, compliance recording, and ongoing optimisation into a managed service create defensible recurring revenue and deeper customer relationships.
The Road Ahead: Teams Phone Mobile
Microsoft’s Teams Phone Mobile initiative — which ties a user’s mobile SIM number to their Teams identity so that calls made from the native phone dialer route through Teams — is the next frontier. The feature requires an Operator Connect partner (currently Liquid Intelligent Technologies in SA) and eSIM or dual-SIM capable devices. Adoption in South Africa is early-stage, constrained by limited eSIM penetration in mid-range smartphones and RICA SIM registration requirements.
For forward-looking resellers, Teams Phone Mobile represents a convergence play — unifying fixed, softphone, and mobile calling under a single Teams identity. Early movers who partner with Liquid and position Teams Phone Mobile alongside compliance recording and managed services will capture the enterprise mobility segment as eSIM adoption matures.
Building a Teams Voice Practice
The opportunity for South African resellers is substantial. Teams voice is not a product sale — it is a practice. The reseller who can assess a customer’s existing telephony infrastructure, recommend the right integration path (Operator Connect for simplicity, Call2Teams for managed flexibility, Direct Routing for full control), deploy the solution, bundle compliance recording, and provide ongoing monitoring and support builds a relationship that generates recurring revenue for years. The technology is mature, the SA provider ecosystem is established, and the customer demand is clear. The question for resellers is not whether to offer Teams voice — it is how quickly they can build the capability to deliver it.
About the Author
Mechelle Gindra
Mechelle Gindra is the managing editor and lead content strategist at Telecoms-Channel, South Africa's dedicated intelligence platform for telecoms resellers, ICT distributors, and channel partners. She oversees the editorial team's AI-assisted content production pipeline, ensuring vendor news, market analysis, and regulatory updates are accurate, timely, and actionable for the SA telecoms channel community. With deep expertise in the South African telecoms reseller ecosystem, Mechelle directs coverage of vendor partner programmes, ICASA regulatory developments, wholesale market dynamics, and channel business strategy. She is responsible for maintaining Telecoms-Channel's editorial standards, fact-checking processes, and corrections policy.
