Direct answer
Every claim is sourced below
Enterprises with hybrid infrastructure should pick a hybrid UCaaS model that keeps regulated voice and call recording on a private edge or on-premises session border controller, while routing meetings, messaging, and PSTN trunks through the public cloud [1][2]. About 88% of organizations now run hybrid IT, making this the default pattern for regulated or multi-site deployments [3].
Segment fit matrix
| Feature | Regulated enterprise | Multi-site global | Cisco/Avaya brownfield |
|---|---|---|---|
| Private SBC for SIP trunking | ✅ Required | 🟡 Recommended | ✅ Required |
| On-premises call recording vault | ✅ Required | 🟡 Recommended | 🟡 Recommended |
| Cloud meetings and messaging | ✅ Required | ✅ Required | ✅ Required |
| Local survivability gateway | ✅ Required | ✅ Required | ✅ Required |
| SD-WAN with QoS marking | ✅ Required | ✅ Required | 🟡 Recommended |
| Direct routing to Microsoft Teams | 🟡 Recommended | 🟡 Recommended | — Skip |
| Phased migration tooling | ✅ Required | ✅ Required | ✅ Required |
Key terms
Provider model
Deployment combining a cloud UCaaS tenant with on-premises session border controllers or local survivability gateways.
Technical dependency
On-premises appliance that secures SIP signaling and provides PSTN failover for cloud voice.
Technical dependency
Edge device that keeps internal calls running when the WAN link to the cloud UCaaS provider fails.
Compliance requirement
Regulatory rule requiring call recordings or PII to remain stored in a specific country or region.
Outcome metric
Pattern where steady-state load runs on private infrastructure and spikes overflow to public cloud.
Providers to consider
Webex Calling is built for hybrid voice with explicit on-premises survivability and dedicated instance options. With 12+ million cloud calling users worldwide, it is the obvious fit when there is an existing Cisco UCM or CUBE footprint to preserve.
Teams Phone supports Direct Routing through customer-owned SBCs, so enterprises can keep carrier contracts and PSTN breakout on-premises while running the call control in M365. With 320 million Teams MAU, the user-side rollout is mostly already done.
RingCentral fits hybrid enterprises that want a managed cloud tenant plus BYO carrier through SBC integration. Ten years as a Gartner Magic Quadrant Leader signals the operational maturity needed for global multi-site hybrid rollouts.