Vendor links go through /go/ redirects. None of them pays us today; if one starts to, it will be marked “(paid link)”. Money never changes which tools we list or how we rank them. How we make money
Retell AI vs Sierra
What each vendor publishes about price, minutes, compliance and integrations, side by side. Checked Oct 26, 2026. We have not tested either product; every fact links back to its source on the vendor page.
The differences in short
- Retell AI publishes a monthly price (Free); Sierra does not.
- They name no industry in common (neither names a specific industry).
- Retell AI states hipaa; Sierra does not say so on the pages we checked.
- Retell AI states appointment booking; Sierra does not say so on the pages we checked.
- BAA: Retell AI say they sign one.
Side by side
| Fact | Retell AI | Sierra |
|---|---|---|
| Type | Voice agent platform | Enterprise voice AI |
| Starts at | Free | Quote |
| Billing model | Pay as you go | Quote only |
| Per-minute rate | $0.07 | Not published |
| Price per call | Not published | Not published |
| Included on entry plan | Not published | Not published |
| Overage | Not published | Not published |
| Free plan / trial | $10 free credits | Not stated |
| HIPAA | BAA available | Not stated |
| Languages | Not published | 55+ languages |
| Human backup | Transfers to your team | Not stated |
| Spanish / bilingual | Not stated | Not stated |
| After-hours / 24/7 | Not stated | Not stated |
| Appointment booking | Yes (vendor states it) | Not stated |
| CRM integration | Not stated | Not stated |
| Build style | No-code and API | Not published |
| Telephony included | Yes | Not published |
| Bring your own carrier / SIP | Yes | Not published |
| Choice of LLM | Yes | Not published |
| Choice of voice provider | Yes | Not published |
| Latency (vendor claim) | ~600ms | Low-latency voice (no figure published) |
| Concurrency | 20 free concurrent calls; no cap on Enterprise | Not published |
| Outbound calling | Yes | Yes |
| White label | Not published | Not published |
| Contact-center integrations | Not published | Not published |
| Integrations | API, Call transfer, Appointment booking | Not published |
| Industries named | General small business | General small business |
| Contract | Not published | Not published |
| Checked | Oct 26, 2026 | Oct 26, 2026 |
| Website | Visit | Visit |
Summaries
Retell AI: Pay-as-you-go voice agent platform for developers; component pricing for infra, voices, LLM and telephony.
Sierra: Enterprise customer-experience AI agents with a voice product for inbound and outbound calls in 55+ languages.
Keep comparing
Sources: Retell AI listing and Sierra listing, each with the vendor URLs we read. Spotted an error? Send a correction.