On-Premise PBX Overview
On-premise PBX systems (Avaya, Cisco, Mitel) run on hardware installed at your location, connected to PSTN via PRI or SIP trunks. The organization owns the equipment, manages software updates, and maintains spare parts inventory. Capital costs range from $500–$1,500 per handset, plus ongoing maintenance contracts of 15–20% of hardware value annually.
Cloud Phone System Overview
Cloud phone systems (RingCentral, Microsoft Teams Phone, Zoom Phone, Nextiva) host all call processing in the vendor's data centers. Organizations pay a per-seat monthly subscription ($20–$45/user/month) that includes voice, video, messaging, and mobile apps. No on-site hardware is required beyond IP phones or softphone applications.
Total Cost of Ownership Comparison
For a 100-user deployment over 5 years: on-premise PBX typically costs $150,000–$250,000 (hardware + maintenance + SIP trunks + IT labor). Cloud phone costs $120,000–$270,000 (subscriptions only, no hardware CapEx). The break-even point is usually 3–4 years, after which cloud costs accumulate while on-premise hardware is paid off — but the on-premise system is also aging toward replacement.
When to Choose Each
Choose on-premise PBX when you have in-house telecom expertise, strict data sovereignty requirements, highly customized call flows that cloud platforms cannot replicate, or very high call volumes where per-seat pricing is unfavorable. Choose cloud phone when you need rapid deployment, multi-location support, remote workforce enablement, or want to eliminate hardware lifecycle management.
Common Pitfalls
Comparing monthly cloud costs to paid-off PBX hardware ignores the hidden costs of aging systems: security patches, spare parts scarcity, and inability to support modern features. On the cloud side, not accounting for internet quality requirements and E911 compliance causes post-migration issues.