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UCaaS Migration · TCO Calculator

Should you keep your PBX or move to UCaaS?

5-year side-by-side total cost of ownership. On-prem includes the PBX refresh you've been delaying. UCaaS includes the price escalators vendors don't put on the sales slide. Get a board-ready breakdown.

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The number most TCO models miss: the PBX refresh hiding in your 5-year window. Cisco, Mitel, Avaya, and NEC platforms typically refresh on a 7-10 year cycle, and the upgrade costs $300-600 per seat in hardware and license fees — comparable to ~2 years of UCaaS subscription paid in a single quarter. If your PBX is 5+ years old today, that capex hits before year 3.

Your Environment

Seven fields. We'll model the rest.

Active phone users. Don't count rooms or break room phones.
Physical sites. Each adds infrastructure overhead on-prem.
Drives when the next refresh hits in the 5-year window.
Hiring trend. Negative = workforce shrinking.
Affects refresh cost and annual maintenance %.
Mid-market typically lands on Standard.
Longer terms unlock 10-25% discount but reduce flexibility.
5-Year Total Cost of Ownership
Calculating...
On-Prem Path
Keep / refresh PBX
$0 / 5 years
$0 in year 1 · $0 per seat / year avg
Refresh capex (years hit)$0
Annual maintenance (SmartNet)$0
SIP trunks + PSTN$0
Internal IT staff allocation$0
Software upgrades + patches$0
Facility (rack, power, cooling)$0
⚠ Refresh impact
—
UCaaS Path
Cloud subscription
$0 / 5 years
$0 in year 1 · $0 per seat / year avg
Per-seat subscription$0
— / seat / mo—
Implementation + onboarding$0
Number porting (one-time)$0
Internet uplift + redundancy$0
Reduced IT staff (savings)$0
Annual price escalation included6%/yr

Year-by-Year Spend

Cumulative cost trajectory. The crossover point — if any — is when UCaaS becomes cheaper.

Year-by-Year Breakdown

Where the money goes each year. The winner column shows which path is cheaper that year.

Year Seats On-Prem cost UCaaS cost Delta Cumulative on-prem Cumulative UCaaS
▸ See all assumptions and TCO model

All numbers are vendor-neutral midpoints based on published list pricing, Gartner UCaaS Magic Quadrant data, and reseller/integrator quotes. Adjust against your specific reality before making a procurement decision. This is a planning tool, not a binding quote.

On-prem cost components

  • Refresh capex: $350-550/seat by PBX tier (Entry $350, Mid $450, Enterprise $550). Refresh occurs at year (10 − current age) within the 5-year window, with a minimum of year 1 if already overdue.
  • Annual maintenance: 18-22% of refresh capex per year (Entry 18%, Mid 20%, Enterprise 22%).
  • SIP trunks: $28/channel/mo, channel-to-seat ratio of 1:3.5.
  • PSTN / DID fees: $0.85/DID/mo, one DID per seat.
  • Internal IT staff: 0.5 FTE base + 0.0008 FTE per seat, loaded at $110K/yr.
  • Software upgrades/patches: 5% of refresh capex in years 2 and 4.
  • Facility (rack, power, cooling): $1,500/year/location.

UCaaS cost components

  • Per-seat subscription (Standard tier midpoint): $32/seat/mo on a 3-year term. Basic $20, Premium $52.
  • Term discount: 1-year baseline, 3-year -15%, 5-year -25%.
  • Annual price escalation: +6%/yr (typical vendor renewal increase).
  • Implementation: $95/seat one-time, with a $7,500 fixed minimum.
  • Number porting: $8/DID one-time, year 1.
  • Internet uplift / redundancy: $350/location/mo.
  • IT staff reduction: 30% of on-prem staff cost (PBX admin time freed up).

Growth handling

  • Seats grow at the specified rate each year. UCaaS scales linearly with seat count.
  • On-prem capacity additions trigger if seat count exceeds 15% over the refresh capacity (modeled as a step-cost in license packs).
  • Negative growth: UCaaS scales down (seat reduction at renewal), on-prem maintenance does not reduce until next refresh.

What this calculator does NOT include

  • Productivity gains from UCaaS features (presence, mobile, integrations) — real but hard to quantify universally.
  • Hidden migration costs (training, change management, integration to CRM / ticketing).
  • Compliance / data residency premiums for specific industries.
  • Contact center seat add-ons (priced separately from basic UCaaS).
  • E911 / Kari's Law compliance costs (mandatory but vendor-included for most modern UCaaS).

📄 Download the TCO breakdown

PDF includes your full 5-year cost comparison year-by-year, the breakeven analysis, all assumptions used, and a 6-item vendor evaluation checklist to bring to UCaaS conversations.

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