The short version
On-prem PBX often looks cheaper when only the monthly bill is compared. UCaaS often looks better when hardware refresh, support, mobility, resilience and administration are included.
| Cost area | PBX | UCaaS |
|---|---|---|
| Hardware | Up-front and refresh cycles | Usually lower up-front hardware |
| Support | Local maintenance and vendor lifecycle | Subscription support and platform updates |
| Resilience | Depends on site power and connectivity | Depends on internet and provider resilience |
| Mobility | Often added later | Usually part of the platform |
Build a real five-year model
Include the items that are easy to miss: porting, training, call-flow redesign, old handset replacement, internet failover, admin time, moves/adds/changes and what happens if the office loses power.
Do not ignore risk
If customers cannot call during an outage, that has a cost. For many businesses, the resilience and flexibility of UCaaS are part of the commercial case.