# Retell AI vs Sierra

**Leader by vioscaleAI score:** Retell AI

| Attribute | Retell AI | Sierra |
|---|---|---|
| **vioscaleAI score** | 79.3 (72% (medium)) | 55.3 (44% (low)) |
| content.faq | `[{"answer":"A system for designing and deploying intelligent voice agents that handle inbound and outbound calls, integrate with CRMs and business systems, and route interactions to human agents when needed. Agents can be built via visual canvas or API and operate across existing phone infrastructure. It is indexed under Voice AI Agents.","source":"https://www.retellai.com","question":"What is Retell AI?","confidence":0.6},{"answer":"Retell AI does not publish its prices. Pricing is quoted on request, across 2 plans (Pay-as-you-go and Enterprise), so the figure depends on your seat count and requirements. We record this as a pricing-transparency signal rather than guessing a number. Pricing changes often, so verify at source before relying on it.","source":"https://www.retellai.com/ar/pricing","question":"How much does Retell AI cost?","confidence":0.6},{"answer":"Retell AI supports the web, iOS and Android. Platforms we have not confirmed are simply not listed here rather than ruled out.","source":"https://www.retellai.com","question":"What platforms does Retell AI support?","confidence":0.6},{"answer":"We have only confirmed a cloud / SaaS deployment for Retell AI, so it appears to be vendor-hosted. If a self-hosted option exists we have not found it documented publicly.","source":"https://www.retellai.com","question":"Can Retell AI be self-hosted?","confidence":0.6},{"answer":"We have confirmed 45 integrations for Retell AI, including Twilio, Vonage, Telnyx, Salesforce, HubSpot, Zoho CRM, Zapier and n8n, plus 37 more. This is what we could verify from public sources, so the vendor may support others we have not indexed.","source":"https://www.retellai.com","question":"What does Retell AI integrate with?","confidence":0.6},{"answer":"We have independently confirmed SOC 2, ISO 27001, HIPAA and GDPR for Retell AI. Certifications we do not list are ones we have not been able to verify from public sources, which is not the same as Retell AI not holding them. Always confirm compliance directly before you rely on it.","source":"https://www.retellai.com","question":"What security certifications does Retell AI have?","confidence":0.6},{"answer":"Retell AI is available worldwide. Its primary markets are the United States, the EU and the United Kingdom. The vendor is headquartered in the United States.","source":"https://www.retellai.com/ar/pricing","question":"Where is Retell AI available?","confidence":0.75}]` | `[{"answer":"A platform for building and deploying AI agents across chat, voice, email, SMS, WhatsApp, and ChatGPT. Includes a no-code agent builder, conversation analytics, and automated agent optimization capabilities with enterprise-grade security and compliance. It is indexed under Voice AI Agents.","source":"https://sierra.ai/resources/podcasts/bret-taylor-of-sierra-on-ai-agents-outcome-based-pricing-and-the-openai-board","question":"What is Sierra?","confidence":0.6},{"answer":"Sierra does not publish its prices. Pricing is quoted on request, so the figure depends on your seat count and requirements. We record this as a pricing-transparency signal rather than guessing a number. Pricing changes often, so verify at source before relying on it.","source":"https://sierra.ai/resources/podcasts/bret-taylor-of-sierra-on-ai-agents-outcome-based-pricing-and-the-openai-board","question":"How much does Sierra cost?","confidence":0.6},{"answer":"We have confirmed browser-based access to Sierra. That is the extent of what we could verify from public sources, so it may well offer desktop or mobile clients we have not indexed.","source":"https://sierra.ai/resources/podcasts/bret-taylor-of-sierra-on-ai-agents-outcome-based-pricing-and-the-openai-board","question":"What platforms does Sierra support?","confidence":0.6},{"answer":"We have only confirmed a cloud / SaaS deployment for Sierra, so it appears to be vendor-hosted. If a self-hosted option exists we have not found it documented publicly.","source":"https://sierra.ai/resources/podcasts/bret-taylor-of-sierra-on-ai-agents-outcome-based-pricing-and-the-openai-board","question":"Can Sierra be self-hosted?","confidence":0.6},{"answer":"We have confirmed 5 integrations for Sierra, including ChatGPT, Voice, Email, SMS and WhatsApp. This is what we could verify from public sources, so the vendor may support others we have not indexed.","source":"https://sierra.ai/resources/podcasts/bret-taylor-of-sierra-on-ai-agents-outcome-based-pricing-and-the-openai-board","question":"What does Sierra integrate with?","confidence":0.6},{"answer":"We have independently confirmed SOC 2, ISO 27001, HIPAA and GDPR for Sierra. Certifications we do not list are ones we have not been able to verify from public sources, which is not the same as Sierra not holding them. Always confirm compliance directly before you rely on it.","source":"https://sierra.ai/fr/product/trust-and-reliability","question":"What security certifications does Sierra have?","confidence":0.7},{"answer":"Sierra is available worldwide. Its primary market is the United States. The vendor is headquartered in the United States.","source":"https://sierra.ai/resources/podcasts/bret-taylor-of-sierra-on-ai-agents-outcome-based-pricing-and-the-openai-board","question":"Where is Sierra available?","confidence":0.75}]` |
| deployment.options | `{"cloud":true}` | `{"cloud":true}` |
| description.long | A cloud-based platform that deploys conversational AI agents to handle inbound and outbound phone calls, including lead qualification, appointment booking, call routing, and CRM integration. | Sierra enables businesses to create and deploy conversational AI agents across voice, chat, email, SMS, and other channels. The platform uses an outcome-based pricing model where customers pay based on business results delivered rather than traditional fixed fees. |
| features.capabilities | `{"soc2_type_ii":true,"pricing_model":"per_minute_usage_based","deployment_model":"no_code_saas_platform","post_call_transcription_and_crm_sync":true,"dynamic_mid_call_api_function_execution":true,"emotion_prosody_and_custom_voice_cloning":true,"outbound_dialing_and_campaign_management":true,"live_human_handoff_and_call_transfer_logic":true,"inbound_reception_and_ivr_routing_replacement":true,"voicemail_detection_and_answering_machine_drops":true,"hipaa_compliance_for_medical_appointment_setting":true,"twilio_vonage_bring_your_own_carrier_byoc_support":true,"sub_second_latency_and_interruption_barget_in_handling":true}` | `{"deployment_model":"no_code_saas_platform","post_call_transcription_and_crm_sync":true,"live_human_handoff_and_call_transfer_logic":true,"hipaa_compliance_for_medical_appointment_setting":true}` |
| integrations.count | 1,000 | 6 |
| integrations.list | `[{"name":"Twilio"},{"name":"Vonage"},{"name":"Telnyx"},{"name":"Salesforce"},{"name":"HubSpot"},{"name":"Zoho CRM"},{"name":"Zapier"},{"name":"n8n"},{"name":"Make"},{"name":"viaSocket"},{"name":"Zendesk"},{"name":"Talkdesk"},{"name":"RingCentral"},{"name":"ServiceTitan"},{"name":"Nice"},{"name":"Workable"},{"name":"Go High Level"},{"name":"OpenDental"},{"name":"Slack"},{"name":"Monday.com"},{"name":"Smartsheets"},{"name":"Shopify"},{"name":"Stripe"},{"name":"Xero"},{"name":"Supabase"},{"name":"Webflow"},{"name":"WhatsApp"},{"name":"ElevenLabs"},{"name":"Minimax"},{"name":"Fish Audio"},{"name":"Cartesia"},{"name":"OpenAI"},{"name":"Google Gemini"},{"name":"Anthropic Claude"},{"name":"Pipedrive","native":true,"category":"crm","direction":"bidirectional"},{"name":"GoHighLevel","native":true,"category":"crm","direction":"bidirectional"},{"name":"Keap","native":true,"category":"crm","direction":"bidirectional"},{"name":"Calendly","native":true,"category":"calendar","direction":"bidirectional"},{"name":"Cal.com","native":true,"category":"calendar","direction":"bidirectional"},{"name":"Google Drive","native":true,"category":"file_storage"},{"name":"Docusign","native":true,"category":"esignature"},{"name":"Jotform","native":true,"category":"forms"},{"name":"Clickup","native":true,"category":"project_management"},{"name":"Azure","native":true,"category":"cloud"},{"name":"Quickbooks","native":true,"category":"accounting"},{"name":"Custom LLM","native":true,"category":"ai"},{"name":"Avaya","native":true,"category":"telephony","direction":"bidirectional"},{"name":"Genesys","native":true,"category":"telephony","direction":"bidirectional"}]` | `[{"name":"ChatGPT"},{"name":"Chat"},{"name":"Voice"},{"name":"Email"},{"name":"SMS"},{"name":"WhatsApp"}]` |
| market.availability | `{"primaryMarkets":["US"],"availabilityScope":"global","availableCountries":[],"notAvailableCountries":[]}` | `{"primaryMarkets":[],"availabilityScope":"global","availableCountries":[],"notAvailableCountries":[]}` |
| platform.support | `{"web":true}` | `{"web":true}` |
| pricing | `{"type":"usage","plans":[{"free":false,"name":"Pay-as-you-go","summary":"$0.07–$0.31/min for voice agents; $0.002+/msg for chat agents","features":["20 concurrent calls included","Full platform access","Drag-and-drop agent builder","Call transfers and routing","CRM integration","Voicemail handling"],"components":[{"per":{"qty":1,"unit":"minute"},"kind":"metered","amount":0.055,"currency":"USD"},{"per":{"qty":1,"unit":"message"},"kind":"metered","amount":0.002,"currency":"USD"}],"description":"Usage-based pricing starting with $10 in free credits","contactSales":false,"includedLimits":{"concurrent_calls":"20"}},{"free":false,"name":"Enterprise","summary":"Custom pricing with volume discounts and dedicated support","features":["Unlimited concurrent calls","HIPAA/BAA compliance","SSO","Custom MSA","Custom DPA","24/7 support","Implementation support","Dedicated account manager"],"description":"Custom pricing for large-scale deployments with dedicated support","contactSales":true}],"summary":"From $0.07/min usage-based pricing. Free tier with $10 credits.","currency":"USD","freeTier":true,"sourceUrl":"https://www.retellai.com/es/pricing","retrievedAt":"2026-10-12T21:50:23.081Z","startingPrice":{"unit":"message","amount":0.002,"currency":"USD"},"billingPeriods":["month"]}` | `{"summary":"Outcome-based pricing model (specific tiers not publicly documented)","sourceUrl":"https://sierra.ai/resources/podcasts/bret-taylor-of-sierra-on-ai-agents-outcome-based-pricing-and-the-openai-board","retrievedAt":"2026-09-22T13:51:11.002Z"}` |
| pricing.free_tier | yes | - |
| pricing.model | freemium | commercial |
| pricing.price_level | low | unknown |
| pricing.starting_price | `{"amount":0.002,"currency":"USD"}` | - |
| pricing.transparent | yes | no |
| reliability.sla_pct | 99.9 | - |
| security.certifications | `[{"name":"SOC 2 Type II","level":"Type II","status":"active"},{"name":"ISO 27001","status":"active"},{"name":"HIPAA","status":"active"}]` | `[{"name":"PCI-DSS Level 1","level":"Level 1","status":"active"},{"name":"ISO 27001","status":"active"},{"name":"ISO 42001","status":"active"}]` |
| security.fedramp | - | yes |
| security.gdpr | yes | yes |
| security.hipaa | yes | yes |
| security.iso27001 | yes | yes |
| security.pci | - | yes |
| security.soc2 | yes | yes |
| security.trust_center | - | https://sierra.ai/de/product/trust-and-reliability |

## Capabilities (Voice AI Agents)

| Capability | Retell AI | Sierra |
|---|:--:|:--:|
| **Capabilities** |  |  |
| Deployment model | No code saas platform | No code saas platform |
| Sub second latency and interruption barget in handling | ✓ | - |
| Dynamic mid call API function execution | ✓ | - |
| Live human handoff and call transfer logic | ✓ | ✓ |
| Emotion prosody and custom voice cloning | ✓ | - |
| Inbound reception and ivr routing replacement | ✓ | - |
| Outbound dialing and campaign management | ✓ | - |
| Post call transcription and CRM sync | ✓ | ✓ |
| Voicemail detection and answering machine drops | ✓ | - |
| Twilio vonage bring your own carrier byoc support | ✓ | - |
| SOC2 type ii | ✓ | - |
| HIPAA compliance for medical appointment setting | ✓ | ✓ |
| Pricing model | Per minute usage based | - |

*Source: vioscaleAI. Generated 2026-10-16T20:16:27.087Z. "-" = undocumented, not absent.*