Features, pricing, and fit
Compare PolyAI Voice Assistants and Sierra Agent on voice capabilities, pricing, and fit.
Compare PolyAI and Sierra Agent for AI phone agents, Contact-center AI, then match channels, workflows, and deployment models to your call flow.
Enterprise voice-and-chat platform with Agent Studio, a Git-oriented Python ADK, REST APIs, knowledge/flows, and analytics.
Enterprise service teams that need managed voice agents plus visual, code-first, or programmatic build surfaces.
Explore its buying criteria: AI phone agents · Contact-center AI.
Customer-service agent platform for inbound/outbound voice, messaging, email, live assist, and ChatGPT channel publishing.
CX organizations that want one agent model across voice and digital channels with brand-persona controls.
Explore its buying criteria: AI phone agents · Contact-center AI.
Both profiles checked 2026-09-04.
Use the table below to compare each provider’s documented scope.
Before you decide
PolyAI: Not publicly documented Sierra Agent: Outcome-based pricing tied to agreed results; Sierra also describes blended consumption pricing for routing or greeter interactions. Ask both vendors to quote the same expected workload, required channels, and implementation scope. Include required subscriptions and usage charges before comparing the total; the listed starting prices alone may cover different work.
The recorded knowledge and data sources for PolyAI include Not publicly documented. For Sierra Agent, they include Not publicly documented. Ask each provider to demonstrate access for the exact systems you use, with permissions, freshness, and failure behavior. A source missing from this directory is not proof that a provider cannot support it.
Use the same representative calls, approved instructions, and escalation rules in both pilots. How does it handle interruption and uncertainty? Which actions can it complete, and which require approval? What context reaches a human during transfer? Record conversation quality, completed tasks, human handoffs, and total cost in the buyer worksheet. Check these specific cautions before launch: PolyAI: Confirm current architecture, availability, call controls, data handling, language coverage, and complete cost in a scoped pilot. Sierra Agent: Public voice detail is limited. Confirm telephony, transfer, recording, retention, language, and exact billable outcome.
Record your requirements and pilot results in the buyer worksheet →
Swipe or scroll the table to see every column.
| Criterion | PolyAI Voice Assistants | Sierra Agent |
|---|---|---|
| Provider type | Enterprise contact-center voice AI | Enterprise customer-service agent platform |
| Best fit | Enterprise service teams that need managed voice agents plus visual, code-first, or programmatic build surfaces. | CX organizations that want one agent model across voice and digital channels with brand-persona controls. |
| Key capabilities | realtime voice conversations; tool or workflow integration; call controls | conversations; backend actions; guardrails; analytics; multi-channel deployment |
| Team sizes | enterprise; contact centers | enterprise |
| Call surfaces | phone / PSTN; API / SDK | voice; chat; digital customer service |
| Voice stack | Cascaded ASR-LLM-TTS architecture | Not publicly documented |
| Telephony | Not publicly documented | Not publicly documented |
| Call controls | Not publicly documented | Not publicly documented |
| Languages | Not publicly documented | Not publicly documented |
| Integrations | Not publicly documented | Not publicly documented |
| Knowledge and data | Not publicly documented | Not publicly documented |
| Pricing model | Not publicly documented | Outcome-based pricing tied to agreed results; Sierra also describes blended consumption pricing for routing or greeter interactions. |
| Pricing signal | Not publicly documented. | Outcome-based enterprise pricing; no public rate. |
| Free plan or trial | Not publicly documented | Not publicly documented |
| What stands out | PolyAI exposes three build surfaces—Agent Studio, ADK, and APIs—over shared flows, knowledge, tools, and deployments; its voice path documents configurable ASR and TTS providers around the agent service. | Sierra pairs channel-spanning agents and configurable Voice Personas with an outcome-based commercial model whose billing is tied to agreed task results; routing/greeter cases may use consumption pricing. |
| Considerations | Confirm current architecture, availability, call controls, data handling, language coverage, and complete cost in a scoped pilot. | Public voice detail is limited. Confirm telephony, transfer, recording, retention, language, and exact billable outcome. |
Enterprise service teams that need managed voice agents plus visual, code-first, or programmatic build surfaces.
PolyAI exposes three build surfaces—Agent Studio, ADK, and APIs—over shared flows, knowledge, tools, and deployments; its voice path documents configurable ASR and TTS providers around the agent service.
CX organizations that want one agent model across voice and digital channels with brand-persona controls.
Sierra pairs channel-spanning agents and configurable Voice Personas with an outcome-based commercial model whose billing is tied to agreed task results; routing/greeter cases may use consumption pricing.
Verify current pricing, limits, security, and required integrations directly with each provider before purchasing.
Test recognition, speech quality, interruptions, language switching, tool use, and human transfer with your own calls in the required language. Availability can vary by model, plan, and phone route.
DocsBot documents multilingual voice workflows and Japanese support. Verify the exact voice, phone path, and transfer behavior in your pilot. Review DocsBot language information ↗
Other providers’ language claims reflect cited vendor material; confirm Japanese and other required languages directly with each provider.
Listing does not imply endorsement or a performance guarantee. This directory is published by DocsBot. Editorial policy
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