Twilio ConversationRelay pricing (2026): voice costs, LLM fees, and a 10,000-minute example
Twilio ConversationRelay costs $0.07/minute, with voice charges calculated separately. Your own LLM provider also bills for model usage. The headline rate is therefore only part of a phone agent's cost. Twilio conversational AI pricing, accessed 2026-09-10.
For US inbound local calls, the published arithmetic starts at $0.0785/minute plus LLM usage and $1.15/month for a number. This is a floor, not a confirmed complete price: the fetched pages do not establish whether STT and TTS sit inside ConversationRelay's fee. Twilio US voice pricing and ConversationRelay pricing, accessed 2026-09-10.
How ConversationRelay's pricing model works
ConversationRelay connects the voice conversation to your application and LLM backend. You budget its service fee, the telephone connection, number rental, and your model provider's bill separately. This structure suits teams that want to keep their own AI backend, but it requires a component-level budget.
Twilio's pricing page explicitly says, “Voice costs are calculated separately.” Its documentation describes the customer application as the AI backend. LLM spending depends on your provider and usage; a fixed LLM cost per call is not computable from these pages. ConversationRelay pricing and ConversationRelay documentation, accessed 2026-09-10.
| US local call direction | ConversationRelay | Voice usage | Computed floor before number rental |
|---|---|---|---|
| Inbound | $0.07/min | $0.0085/min | $0.0785/min + LLM |
| Outbound | $0.07/min | $0.014/min | $0.084/min + LLM |
Sources: Twilio conversational AI pricing and Twilio US voice pricing, accessed 2026-09-10. These are derived floors, with speech inclusion unresolved.
What's included vs. billed separately
| Component | Published treatment |
|---|---|
| ConversationRelay service | $0.07/min |
| Speech recognition and text-to-speech | No fetched page explicitly establishes inclusion or exclusion within that fee |
| LLM | Customer's own provider bills separately; amount depends on usage |
| US inbound local voice | $0.0085/min separately |
| US outbound local voice | $0.014/min separately |
| US local number | $1.15/month |
| Media Streams | Separately listed product at $0.0044/min; not established as a required ConversationRelay surcharge |
Sources: Twilio voice pricing, US voice pricing, conversational AI pricing, and ConversationRelay documentation, accessed 2026-09-10.
Do not infer that speech is included simply because the pricing page lacks a separate ConversationRelay speech line. Equally, standalone speech prices do not prove that those charges apply to ConversationRelay. Confirm your selected speech configuration before treating the floor as a budget.
Media Streams also deserves separate treatment. A separately listed product is not automatically an extra fee on every ConversationRelay minute. The worked floor below does not add it, because the fetched material does not establish that requirement.
For a broader framework, see AI phone agent cost and the voice AI cost breakdown.
Worked example: 10,000 minutes a month
Use 2,000 calls × 5 connected minutes = 10,000 connected minutes/month. Assume US inbound local calls, one primary included language, one phone number, and no transfers, hold, or voicemail minutes. Concurrency stays at or below 10; that is a workload assumption, not a verified Twilio limit.
This is illustrative planning arithmetic, not a quote. We apply the published rates directly to connected minutes, without inventing a rounding adjustment.
| Line item | Calculation | Monthly amount |
|---|---|---|
| ConversationRelay | 10,000 × $0.07 | $700.00 |
| Inbound local voice | 10,000 × $0.0085 | $85.00 |
| Local number | One number | $1.15 |
| Known subtotal | $700 + $85 + $1.15 | $786.15 |
| Customer's LLM | Provider usage bill | Not computable from the fetched pages |
| Any speech configuration surcharge | Inclusion and surcharges unconfirmed | Not computable from the fetched pages |
Rate sources: Twilio conversational AI pricing and Twilio US voice pricing, accessed 2026-09-10.
The planning result is $786.15/month plus LLM, subject to the unresolved speech scope and actual metering. Recording and other optional services are outside this example. An invoice could differ if the measured service duration differs from connected call duration.
Gotcha checklist
- Keep voice outside the headline fee. Match the carrier rate to the country, direction, and number type of the actual calls.
- Confirm speech inclusion in writing. No fetched page says whether STT/TTS sit inside the ConversationRelay fee or identifies applicable premium speech surcharges.
- Budget the LLM separately. The customer supplies the AI backend. Your provider's usage bill cannot be inferred from connected minutes alone.
- Treat minute rounding as unverified. Search snippets suggest partial minutes round up to a full minute per leg. That rule could not be verified on a first-party page: support pages were empty or inaccessible.
- Check both billing meters. The fetched discrepancy documentation only establishes rounding according to the applicable pricing model. ConversationRelay's own billing increment is not stated. Twilio usage documentation, accessed 2026-09-10.
- Do not automatically stack Media Streams. Confirm which products your implementation actually uses before adding another metered service.
- Keep rental and optional usage visible. A per-minute floor excludes number rental; transfers, recording, and other services need their own budget where applicable.
How ThunderPhone prices differ
ThunderPhone publishes a complete engine rate that includes speech recognition, language model, and voice. It is prepaid, pay as you go, with no subscription, seat, or platform fee. Telephony remains separate. See ThunderPhone pricing explained.
You can connect a Twilio number to ThunderPhone, keep Twilio telephony, and pay ThunderPhone's engine rate instead of the ConversationRelay fee. ThunderPhone adds no import or monthly charge for that number; Twilio continues billing its carrier usage and rental.
Using the same published Twilio inbound local rate gives this planning comparison:
| Engine with Twilio telephony | Engine rate | Engine + inbound voice per minute | 10,000 minutes + $1.15 number |
|---|---|---|---|
| Spark | $0.02 | $0.0285 | $286.15 |
| Bolt | $0.05 | $0.0585 | $586.15 |
| Storm | $0.09 | $0.0985 | $986.15 |
Sources: ThunderPhone pricing and Twilio US voice pricing, accessed 2026-09-10. Totals combine engine usage, inbound local voice, and number rental.
These combinations assume the quoted inbound voice rate applies to your connection. Any additional carrier routing charges are not computable from the published pages; confirm the actual connection's billing before relying on these totals.
ThunderPhone's model usage is included in these engine totals. Premium voice or language paths can add up to $0.03/minute, non-stacking. Long prompts and optional features can also change the rate. ThunderPhone meters in quarter-minute increments with a quarter-minute minimum; the carrier meters its own usage separately.
Spark and Bolt produce lower known subtotals here. Storm's subtotal exceeds ConversationRelay's known subtotal, whose LLM bill and speech scope remain unresolved. This arithmetic does not establish equivalent performance or a final invoice comparison.
ConversationRelay can suit a team that specifically wants to retain its own LLM backend within a Twilio implementation. ThunderPhone suits buyers who want speech and model usage bundled into the engine rate. Compare the wider market in cheapest AI voice agent, voice AI pricing comparison, and the voice AI price index.
FAQ
How much does Twilio ConversationRelay cost per minute?
The service fee is $0.07/minute, before voice and your LLM bill. US inbound local voice brings the computed floor to $0.0785/minute, excluding number rental and unresolved speech charges. Twilio pricing and US rates, accessed 2026-09-10.
Does ConversationRelay include STT and TTS?
The fetched pages do not establish whether either is included in the fee. Confirm your speech configuration and any surcharges; neither inclusion nor exclusion should be assumed.
Is the LLM included in ConversationRelay pricing?
No; your own LLM provider bills for model usage separately. The customer supplies the AI backend. A complete model bill is not computable from Twilio's published minute rate. ConversationRelay documentation, accessed 2026-09-10.
What does the inbound example cost monthly?
The known subtotal is $786.15, plus LLM usage and any applicable unresolved charges. The worked table includes ConversationRelay, inbound local voice, and number rental using the cited Twilio rates.
Can I keep my Twilio number with ThunderPhone?
Yes; connect the number and retain Twilio as your telephony provider. You pay ThunderPhone's engine rate instead of ConversationRelay's fee. The Twilio integration explains the connection; the table above shows the conditional combined costs.
Sources and freshness
Every third-party figure on this page was checked against the linked first-party pages on September 10, 2026:
- Twilio conversational AI pricing, accessed 2026-09-10.
- Twilio voice pricing, accessed 2026-09-10.
- Twilio US voice pricing, accessed 2026-09-10.
- ConversationRelay documentation, accessed 2026-09-10.
- Twilio call-log usage discrepancies, accessed 2026-09-10.
- ThunderPhone pricing, accessed 2026-09-10.
This page is documentation-based; no account, invoice, or live call was tested. Speech inclusion, exact Twilio rounding increments, and connection-specific carrier extras remain unverified. A complete ConversationRelay total is not computable from the fetched pages.