Three calls. Three wins. Half the turns.
We ran the same mystery-shopper call against our agent and ThunderPhone’s Spark tier three times, judged blind, and counted what happened.
Calls won
Avg. turns to resolve
Slowest response
How we ran it.
Same shopper persona, same goal, same script, placed against our POC engine (Deepgram, Claude Haiku, Kokoro) and ThunderPhone’s Spark tier (GPT-4o-mini) — their entry pricing tier, not their higher Bolt or Storm tiers. A blind judge scored each transcript on turns to resolution and response latency. Our first pass came back 2–1 because of a bug in how we scripted the shopper; we fixed it and reran clean, which is the 3–0 result above.
Pricing.
The two price lists have a similar structure: a per-minute rate for the AI engine in three tiers, with optional add-ons planned for later. Phone agents from 2 cents a minute. Lite 2 cents, Standard 5 cents and Pro 9 cents per minute, all available now.
| Vendor | Tier | Per minute | Included | Billed separately |
|---|---|---|---|---|
| CallDeskTech | Lite | 2¢ | AI engine | Your phone carrier (bring your own), or phone numbers from us as an extra |
| CallDeskTech | Standard | 5¢ | AI engine | Your phone carrier (bring your own), or phone numbers from us as an extra |
| CallDeskTech | Pro | 9¢ | AI engine | Your phone carrier (bring your own), or phone numbers from us as an extra |
| ThunderPhone | Spark | 2¢ | AI engine | Telephony; premium voices +3¢/min; long prompts +1¢/min |
| ThunderPhone | Bolt | 5¢ | AI engine | Telephony; premium voices +3¢/min; long prompts +2¢/min |
| ThunderPhone | Storm | 9¢ | AI engine | Telephony; premium voices +3¢/min; long prompts +2¢/min |
- ThunderPhone: Hold time: 2¢/min
- ThunderPhone: Phone numbers from ThunderPhone: $1/month plus 1¢/min inbound
- ThunderPhone: Bring your own carrier or SIP is supported; telephony is not part of the tier rate
- CallDeskTech: transfers, DTMF, testing and monitoring are included in the per-minute rate, with no per-booking or per-transfer fees on the tiers. Phone numbers from us are a paid extra on every plan; bringing your own is free.
- Optional add-ons are coming soon and cannot be bought yet; amounts will be announced when they launch. See the pricing page.
ThunderPhone prices are their published list prices, retrieved 2026-10-02 from https://thunderphone.com/pricing. Prices change; check their page for the current numbers.
Where they’re actually ahead.
ThunderPhone is genuinely simpler to set up — a single prompt, no flow builder required. If you want something running in two minutes and don’t need branching logic, that’s a real advantage.
They also ship 47 languages out of the box. We only tested this benchmark in English, so we can’t compare language quality head to head here — see our language coverage on the Retell comparison instead.
ThunderPhone also advertises 99.4% accuracy on their Storm tier. That figure is measured on their own dataset, not an independent benchmark, and this test didn’t isolate that specific claim — we’re noting it so you can weigh it yourself, not disputing it.
Hear it yourself.
Place a real call to one of our demo agents. No account required.