Guide · AI Receptionists
AI receptionist overage rates run from $0.05 a minute to $2.60 — a 50x spread for the exact same overflow
The price of going over your plan is the price you should shop on, because it's the number that moves when business is good — and in this dataset it spans more than fifty-fold.
Re-verified 2026-06-22. Most rates held, but three vendors pulled their cheapest published numbers since this was first written. Synthflow dropped self-serve pricing entirely — it now quotes custom enterprise contracts only (from $30,000/yr), with no per-minute rate at all. ServiceAgent still bills 15 credits a minute, but a credit is now priced at $0.02–$0.04 (not the old $0.01), so its real marginal minute is $0.30–$0.60, not $0.15. And Smith.ai no longer posts its $2.40/extra-call self-serve overage; only the $3/call live-agent handoff survives. The table and copy below reflect this — and the pattern itself (vendors quietly retiring their cheap published rates) is exactly why the overage number is the one to watch.
The sticker price tells you what a quiet month costs. The overage rate tells you what a good month costs — and that’s the one to negotiate on, because the included bucket is exactly what you’ll outgrow when the phone starts ringing. In this dataset the marginal price of one extra minute spans more than fifty-fold: $0.05/min on Vapi at the bottom, $2.60/min on PATLive at the top. Per-call plans tell the same story in a different unit: Upfirst’s published rate runs $0.70 to $1.50 per extra call, while Smith.ai’s last-posted self-serve figure of $2.40/call sat well above it before the company pulled its self-serve tiers.
Two things drive that gap: who answers, and whether the overage rate is “all-in.” Here is the per-minute field, cheapest marginal rate first.
| Vendor | Overage rate | What the rate covers |
|---|---|---|
| Vapi | $0.05/min | Platform fee only — models passed through on top |
| Retell AI | $0.07/min | Published floor of a $0.07–$0.31/min range |
| Trillet | $0.12/min | Flat plan, all-in |
| My AI Front Desk | $0.25/min | 25 credits/min at $0.01/credit |
| Phonely | $0.30/min | Stated $0.25–$0.35/min by plan |
| ServiceAgent | $0.30 → $0.60/min | 15 credits/min; credits now $0.02–$0.04 each |
| Dialzara | $0.48 → $0.35/min | Tiered; cheaper rate on higher plans |
| PATLive | $2.60 → $2.00/min | Live human agents |
The developer platforms own the floor, but the same caveat that haunts their sticker prices haunts their overage rates. Vapi’s $0.05/min is the platform fee; the language model, speech-to-text, and text-to-speech are billed on top, so one extra minute costs more than five cents in practice (we unpack that gap in the true per-minute cost of the developer voice platforms). Retell’s $0.07/min is the published floor of a $0.07–$0.31/min range that moves with your model choice. Synthflow used to sit right here at $0.09/min for its voice engine alone, but it has since pulled self-serve pricing entirely and now quotes custom enterprise contracts only, from $30,000/yr — so it has no published overage rate to compare. If you want a marginal rate you can actually trust, Trillet’s flat $0.12/min on Studio and Agency is now the cleanest all-in number on the board: it doesn’t sprout footnotes. ServiceAgent reads cheap at a glance too, but it is the clearest example of the footnote trap — 15 credits a minute sounds fixed, yet a credit now costs $0.02–$0.04, which puts its real marginal minute at $0.30–$0.60, not the $0.15 a one-cent credit would imply.
The tiered plans reward growth — quietly
A flat overage rate is honest but static. Dialzara does something subtler: it steps the overage down as you climb plans — $0.48/min on Business Lite, $0.45 on Pro, $0.40 on Plus, $0.35/min on Elite. The included bucket grows too (60 minutes to 1,000), so the more you commit, the less every extra minute costs. We walk the tier-by-tier overage savings on Dialzara in detail separately. The same logic appears on per-call plans below.
Per-call overage is a different unit — and Smith.ai is the outlier
Three vendors bill the overage by the call, not the minute, which changes how you should read it. Upfirst charges $1.50 per extra call on Starter, dropping to $1.00, $0.75, and $0.70 per call as you move up to Scale. (AIRA publishes a byte-identical table.) That’s the friendly end, and we put the two head to head in Smith.ai vs Upfirst per-call pricing.
The unfriendly end was Smith.ai at $2.40 per extra call — billed flat, so it didn’t matter whether the call ran twenty seconds or six minutes; you paid $2.40 either way. As of our June re-check, Smith.ai no longer posts that self-serve overage at all: its page now leads with a $500/mo Managed plan and has dropped the self-serve Starter/Basic/Pro tiers the $2.40 rate hung off (a Starter plan once gave you 30 included calls before that overage bit). What survives is the $3/call live-agent handoff Smith.ai stacks on when a human takes over — its own line item, and now the only per-call number the page actually publishes. Treat the $2.40 as a last-known figure, not a current quote; for Smith.ai’s overflow economics today you’re asking sales for one.
The human services are the ceiling, and that’s the point
PATLive sits at the top because a person picks up. Its overage steps down the more you commit — $2.60/min on Basic, $2.35 on Starter, $2.20 on Standard, $2.10 on Premium, and $2.00/min on Pro — and on the Basic plan there are no included minutes, so the very first minute is billed at $2.60. That is not the AI market failing; it’s the cost of the thing the AI plans replace. Put PATLive’s $2.00–$2.60/min next to Trillet’s $0.12 and the gap is the AI-versus-human decision, priced per minute.
The cleanest answer: read the rate, not the headline
If overage is your real risk — seasonal spikes, a marketing push, a viral week — a few numbers matter. Vapi’s $0.05/min is the cheapest marginal minute but the least all-in. Trillet’s flat $0.12/min is now the cheapest trustworthy, all-in marginal minute on the board — the kind of number that doesn’t move on you. (ServiceAgent used to share that spot at $0.15/min, but repricing its credit to $0.02–$0.04 pushed its real rate to $0.30–$0.60.) And Dialzara’s $0.48→$0.35/min taper rewards you for committing before the busy season, not after. Per call, Upfirst’s $0.70–$1.50 is the only self-serve per-call rate still posted at the friendly end; Smith.ai, which used to anchor the expensive end at a flat $2.40/call, has pulled its self-serve tiers and now sells the human handoff ($3/call) by quote. The lesson sharpens with every re-check: the headline price is what a slow month costs, the overage rate is what success costs — and vendors quietly move it, so it’s the one worth shopping.