Smallest.ai Atoms vs Ultravox
Pricing last verified from each vendor's own site.
Verdict
Smallest.ai Atoms starts at $0.05/min and typically lands at $0.09 to $0.21/min depending on models, with $10 free credits and numbers at $10/mo. Ultravox is a flat $0.05/min after 30 free minutes, with Pro at $100/mo for no hard concurrency caps.
- Consider Smallest.ai Atoms if: You want a choice of model stacks, including Smallest's own speech models.
- Consider Ultravox if: You want one flat per-minute rate on a speech-native model.
Factual summary
- Both are listed under Voice AI & Dialers.
- Directly comparable starting prices are not available for both: Smallest.ai Atoms — Pay as you go with $10 in free credits: voice agents from $0.05/min, typically $0.09 to $0.21/min depending on the models chosen (hosting $0.01/min flat, speech-to-text about $0.009/min, LLM at cost, text-to-speech about $0.09/min, or speech-to-speech); phone numbers $10/mo; HIPAA zero data retention add-on $1,000/mo; enterprise custom; Ultravox — Pay as you go: $0/mo with the first 30 minutes free, then $0.05/min, up to 5 concurrent calls; Pro $100/mo (no hard concurrency caps) at $0.05/min; SIP $0.0048/min; Enterprise custom.
- Smallest.ai Atoms lists channels Ultravox does not: sms.
This is a factual comparison drawn from vendor sites, not a recommendation. Which fits depends on your channels, volume and budget.
| Smallest.ai Atoms | Ultravox | |
|---|---|---|
| Summary | Voice AI agent platform with its own speech models, priced per minute by model stack. | Speech-native voice AI model and platform for real-time voice agents, priced per minute. |
| Starting price | See vendor | See vendor |
| Pricing details | Pay as you go with $10 in free credits: voice agents from $0.05/min, typically $0.09 to $0.21/min depending on the models chosen (hosting $0.01/min flat, speech-to-text about $0.009/min, LLM at cost, text-to-speech about $0.09/min, or speech-to-speech); phone numbers $10/mo; HIPAA zero data retention add-on $1,000/mo; enterprise custom | Pay as you go: $0/mo with the first 30 minutes free, then $0.05/min, up to 5 concurrent calls; Pro $100/mo (no hard concurrency caps) at $0.05/min; SIP $0.0048/min; Enterprise custom |
| Model | usage | usage |
| Free trial | — | — |
| Free plan | — | — |
| Channels | phone, sms | phone |
| Last verified | 2026-11-02 | 2026-11-01 |
FAQ
What is the difference between Smallest.ai Atoms and Ultravox?
Smallest.ai Atoms starts at $0.05/min and typically lands at $0.09 to $0.21/min depending on models, with $10 free credits and numbers at $10/mo. Ultravox is a flat $0.05/min after 30 free minutes, with Pro at $100/mo for no hard concurrency caps.
Which is cheaper, Smallest.ai Atoms or Ultravox?
We can't compare entry prices directly. Smallest.ai Atoms: Pay as you go with $10 in free credits: voice agents from $0.05/min, typically $0.09 to $0.21/min depending on the models chosen (hosting $0.01/min flat, speech-to-text about $0.009/min, LLM at cost, text-to-speech about $0.09/min, or speech-to-speech); phone numbers $10/mo; HIPAA zero data retention add-on $1,000/mo; enterprise custom. Ultravox: Pay as you go: $0/mo with the first 30 minutes free, then $0.05/min, up to 5 concurrent calls; Pro $100/mo (no hard concurrency caps) at $0.05/min; SIP $0.0048/min; Enterprise custom.
When should I choose Smallest.ai Atoms over Ultravox?
Consider Smallest.ai Atoms if: You want a choice of model stacks, including Smallest's own speech models. Consider Ultravox if: You want one flat per-minute rate on a speech-native model.
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