---
segment: voice
segment_kind: channel
question: "What is the best AI customer service agent for phone calls?"
page_url: https://ai-agent.review/best-ai-agent-for-customer-service/voice
record_url: https://ai-agent.review/best-ai-agent-for-customer-service/voice.md
tested_performance: not-yet-tested
---

# What is the best AI customer service agent for phone calls?

No independent source establishes any agent in this catalogue as answering customers over phone calls. Ada, Agentforce and Breeze Customer Agent document it in their own material, which is where a shortlist starts rather than where it ends. 18 of the 22 agents reviewed have any published evidence for phone calls; for the rest it is unknown, which means nobody has published it, not that the product cannot do it. Nothing here has been tested by this portal, so treat every name below as a shortlist to validate, not a winner.

## How these groups are formed

1. Agents are grouped by what the cited sources establish for this segment, not scored against each other.
2. An outside source reporting the product in this segment comes first, then the vendor's own documentation, then a documented limitation, then silence.
3. Within a group the order is alphabetical, because the evidence does not support ranking one against another.
4. No agent is dropped: the ones with nothing published are named too.

Groups are derived from the cited claims at build time and describe the evidence, not the products. Nothing here has been tested, so a higher group means more has been established about an agent in this segment, not that it performs better. An agent can be well suited to you and sit in the last group simply because nobody has written about it. Published review-site ratings do not order these groups either: where a record carries one it is cited on the profile, but those ratings score whole products against each other — one vendor's bundled chat widget against another's full help desk — and none of them measures the AI agent on its own.

## An outside source reports it serving this segment

A customer, analyst or journalist with no stake in the sale describes the product working here. This is the strongest evidence the portal holds, and it is still somebody else's deployment, not yours.

No agent in the catalogue is in this group.

## The vendor documents this segment, and nobody else has written about it

The vendor says it serves this segment. That is a reasonable place to start a shortlist and it is not confirmation, because no independent source has reported on it either way.

Listed alphabetically. Position inside a group carries no meaning: these agents are not ranked against each other.

| Agent (A–Z) | Vendor | Evidence for this segment | What puts it here | Customer workflows with evidence |
| --- | --- | --- | --- | --- |
| [Ada](https://ai-agent.review/agents/ada.md) | Ada | Vendor-documented | [Key concepts (Ada docs)](https://docs.ada.cx/docs/welcome/key-concepts) | 0 externally reported, 7 vendor-documented, of 7 |
| [Agentforce](https://ai-agent.review/agents/agentforce.md) | Salesforce | Vendor-documented | [AI customer service agents (Salesforce)](https://www.salesforce.com/service/ai/customer-service-agents/) | 0 externally reported, 7 vendor-documented, of 7 |
| [Breeze Customer Agent](https://ai-agent.review/agents/hubspot-breeze.md) | HubSpot | Vendor-documented | [AI Customer Service Agent — HubSpot](https://www.hubspot.com/products/artificial-intelligence/ai-customer-service-agent) | 0 externally reported, 2 vendor-documented, of 7 |
| [Crescendo](https://ai-agent.review/agents/crescendo.md) | Crescendo | Vendor-documented | [Crescendo — Concierge Agent](https://www.crescendo.ai/agents/concierge) | 2 externally reported, 1 vendor-documented, of 7 |
| [Decagon](https://ai-agent.review/agents/decagon.md) | Decagon | Vendor-documented | [Decagon homepage and linked customer examples](https://decagon.ai/) | 1 externally reported, 6 vendor-documented, of 7 |
| [Five9](https://ai-agent.review/agents/five9.md) | Five9 | Vendor-documented | [Conversational, Generative and Agentic AI](https://www.five9.com/products/capabilities/conversational-generative-agentic-ai) | 2 externally reported, 0 vendor-documented, of 7 |
| [Forethought](https://ai-agent.review/agents/forethought.md) | Forethought (Zendesk) | Vendor-documented | [Forethought Solve](https://forethought.ai/solve/) | 3 externally reported, 0 vendor-documented, of 7 |
| [Genesys Cloud CX](https://ai-agent.review/agents/genesys-cloud-cx.md) | Genesys | Vendor-documented | [About Genesys Dialog Engine Bot Flows - Genesys Cloud Resource Center](https://help.genesys.cloud/articles/about-genesys-dialog-engine-bot-flows/) | 0 externally reported, 2 vendor-documented, of 7 |
| [Kore.ai](https://ai-agent.review/agents/kore-ai.md) | Kore.ai | Vendor-documented | [Channels - Kore.ai Agent Platform documentation](https://koreai.mintlify.app/agent-platform/channels.md) | 1 externally reported, 1 vendor-documented, of 7 |
| [LivePerson](https://ai-agent.review/agents/liveperson.md) | LivePerson | Vendor-documented | [Generative AI Tools — LivePerson](https://www.liveperson.com/products/generative-ai/) | 0 externally reported, 2 vendor-documented, of 7 |
| [NiCE Cognigy](https://ai-agent.review/agents/nice-cognigy.md) | NiCE | Vendor-documented | [Endpoint Reference - Overview \| Cognigy Documentation](https://docs.cognigy.com/ai/agents/deploy/endpoint-reference/overview.md) | 1 externally reported, 1 vendor-documented, of 7 |
| [NiCE CXone](https://ai-agent.review/agents/nice-cxone.md) | NiCE | Vendor-documented | [AI Agents for Self-Service](https://www.nice.com/products/ai-agents-for-self-service) | 3 externally reported, 0 vendor-documented, of 7 |
| [PolyAI](https://ai-agent.review/agents/polyai.md) | PolyAI | Vendor-documented | [PolyAI Docs — documentation index (llms.txt)](https://docs.poly.ai/llms.txt) | 2 externally reported, 1 vendor-documented, of 7 |
| [Sierra](https://ai-agent.review/agents/sierra.md) | Sierra | Vendor-documented | [Channels (Sierra)](https://sierra.ai/product/channels) | 0 externally reported, 7 vendor-documented, of 7 |
| [Sprinklr](https://ai-agent.review/agents/sprinklr.md) | Sprinklr | Vendor-documented | [Sprinklr AI Agents](https://www.sprinklr.com/products/platform/ai-agents/) | 1 externally reported, 1 vendor-documented, of 7 |
| [Talkdesk](https://ai-agent.review/agents/talkdesk.md) | Talkdesk | Vendor-documented | [Talkdesk AI Agents / Multi-Agent Orchestration](https://www.talkdesk.com/contact-center-platform/ai-agents/) | 3 externally reported, 2 vendor-documented, of 7 |
| [Yellow.ai](https://ai-agent.review/agents/yellow-ai.md) | Yellow.ai | Vendor-documented | [Escalation (Yellow.ai docs)](https://docs.yellow.ai/docs/nexus/build/tools/escalation) | 0 externally reported, 2 vendor-documented, of 7 |
| [Zendesk AI Agents](https://ai-agent.review/agents/zendesk-ai-agents.md) | Zendesk | Vendor-documented | [Zendesk AI Agents product overview](https://www.zendesk.com/service/ai/ai-agents/) | 1 externally reported, 6 vendor-documented, of 7 |

## A limitation is documented for this segment

A cited source describes a limit or a bad experience here. It sits below vendor documentation because it is not evidence of fit, and above the agents nobody has written about because somebody at least looked. Read the condition: it may not apply to you at all.

No agent in the catalogue is in this group.

## Nothing published for this segment

No reviewed source places these agents here, by the vendor's own documentation or otherwise. That is a gap in the public record, not a finding against the products, and several of them may suit you.

Listed alphabetically. Position inside a group carries no meaning: these agents are not ranked against each other.

- [Fin](https://ai-agent.review/agents/fin.md)
- [Freddy AI Agent](https://ai-agent.review/agents/freddy-ai.md)
- [Gorgias AI Agent](https://ai-agent.review/agents/gorgias.md)
- [Lyro](https://ai-agent.review/agents/lyro.md)

## Every claim behind these groups

### Ada — Vendor-documented

- Chat, voice, email and social messaging are documented. Voice and social connections use supported external platforms; confirm the intended channel integration. _(Vendor-reported, checked 20 Sept 2026; source: [Key concepts (Ada docs)](https://docs.ada.cx/docs/welcome/key-concepts); claim id: `ada-channels`)_

### Agentforce — Vendor-documented

- Salesforce describes messaging, web, mobile and voice service experiences. Channel availability and setup should be checked for the specific Service Agent offering. _(Vendor-reported, checked 20 Sept 2026; source: [AI customer service agents (Salesforce)](https://www.salesforce.com/service/ai/customer-service-agents/); claim id: `agentforce-channels`)_

### Breeze Customer Agent — Vendor-documented

- HubSpot lists live chat, email, forms, WhatsApp, Facebook Messenger, and inbound voice calls as channels the agent can handle. _(Vendor-reported, checked 20 Sept 2026; source: [AI Customer Service Agent — HubSpot](https://www.hubspot.com/products/artificial-intelligence/ai-customer-service-agent); claim id: `hubspot-breeze-cmp-channels`)_

### Crescendo — Vendor-documented

- Crescendo states its Concierge agent handles "Voice, chat, email, SMS, WhatsApp" from a single AI layer, with a website chat widget, mobile apps and API access also documented. _(Vendor-reported, checked 20 Sept 2026; source: [Crescendo — Concierge Agent](https://www.crescendo.ai/agents/concierge); claim id: `crescendo-cmp-channels`)_

### Decagon — Vendor-documented

- Decagon’s homepage lists chat, email and voice. SMS appears in its Curology customer story; confirm whether that channel is available for your proposed deployment. _(Vendor-reported, checked 20 Sept 2026; source: [Decagon homepage and linked customer examples](https://decagon.ai/); claim id: `decagon-channels`)_

### Five9 — Vendor-documented

- Five9 markets both "Voice AI Agents" for automating routine customer interactions and "Digital AI Agents" providing personalized self-service via chatbots and social messaging. _(Vendor-reported, checked 20 Sept 2026; source: [Conversational, Generative and Agentic AI](https://www.five9.com/products/capabilities/conversational-generative-agentic-ai); claim id: `five9-channels`)_

### Forethought — Vendor-documented

- The vendor lists chat, email, voice, SMS, Slack, mobile apps and a headless API as supported channels. _(Vendor-reported, checked 20 Sept 2026; source: [Forethought Solve](https://forethought.ai/solve/); claim id: `forethought-channels`)_

### Genesys Cloud CX — Vendor-documented

- Genesys documents that bots built in Architect can be integrated into call, chat and message flows, and markets AI agents across voice, text, web, social and WhatsApp. _(Vendor-reported, checked 20 Sept 2026; source: [About Genesys Dialog Engine Bot Flows - Genesys Cloud Resource Center](https://help.genesys.cloud/articles/about-genesys-dialog-engine-bot-flows/); claim id: `genesys-cmp-channels`)_

### Kore.ai — Vendor-documented

- Kore.ai's channel documentation lists digital channels (Slack, LINE, Microsoft Teams, WhatsApp, Messenger, Twilio SMS, Telegram, Zendesk, Instagram, Genesys, Genesys Open Messaging, Email), voice channels (Realtime LLM Voice, Pipeline Voice, VXML IVR, Genesys Audio Connector, AudioCodes), SDK channels (Web SDK, API, Mobile SDK), webhooks, and the AG-UI and Agent-to-Agent protocols. _(Vendor-reported, checked 20 Sept 2026; source: [Channels - Kore.ai Agent Platform documentation](https://koreai.mintlify.app/agent-platform/channels.md); claim id: `kore-ai-cmp-channels`)_

### LivePerson — Vendor-documented

- LivePerson states its AI agents can be built and launched with LLMs 'across messaging and voice', and its Conversational Cloud page names SMS, WhatsApp and voice among supported channels. _(Vendor-reported, checked 20 Sept 2026; source: [Generative AI Tools — LivePerson](https://www.liveperson.com/products/generative-ai/); claim id: `liveperson-cmp-channels`)_

### NiCE Cognigy — Vendor-documented

- Documented endpoints cover web chat, telephony via Cognigy Voice Gateway, WhatsApp, Facebook Messenger, Microsoft Teams, Slack, LINE Messenger, Twilio and Twilio SMS, Intercom, Userlike, Zendesk Sunshine Conversations, Genesys, 8x8, NiCE CXone, RingCentral Engage, Zoom, Azure Bot Services, plus REST, Socket and Webhook endpoints. _(Vendor-reported, checked 20 Sept 2026; source: [Endpoint Reference - Overview \| Cognigy Documentation](https://docs.cognigy.com/ai/agents/deploy/endpoint-reference/overview.md); claim id: `nice-cognigy-cmp-channels`)_

### NiCE CXone — Vendor-documented

- NiCE states its self-service AI agents deliver natural language experiences that are equally fluent over digital or voice channels, with multimodal capabilities blending voice, text, multimedia and device capabilities. _(Vendor-reported, checked 20 Sept 2026; source: [AI Agents for Self-Service](https://www.nice.com/products/ai-agents-for-self-service); claim id: `nice-cxone-cmp-channels`)_

### PolyAI — Vendor-documented

- PolyAI is voice-first — its documentation calls it an "enterprise platform for building voice and chat agents" and its pricing is per minute of voice-agent use — with secondary documented channels covering web chat, SMS and RCS, email, and iOS/Android SDKs (including in-app voice calling). _(Vendor-reported, checked 20 Sept 2026; source: [PolyAI Docs — documentation index (llms.txt)](https://docs.poly.ai/llms.txt); claim id: `polyai-cmp-channels`)_

### Sierra — Vendor-documented

- Vendor-listed channels include phone, website and app chat, WhatsApp, Apple Business Chat, SMS and email. Live Assist supports staff, and Sierra also documents publishing selected agent journeys to ChatGPT. _(Vendor-reported, checked 20 Sept 2026; source: [Channels (Sierra)](https://sierra.ai/product/channels); claim id: `sierra-channels`)_

### Sprinklr — Vendor-documented

- Sprinklr states AI agents operate across "chat, social, voice, messaging, email, and more", moving between voice, chat, email and social while retaining conversation context. _(Vendor-reported, checked 20 Sept 2026; source: [Sprinklr AI Agents](https://www.sprinklr.com/products/platform/ai-agents/); claim id: `sprinklr-channels`)_

### Talkdesk — Vendor-documented

- Talkdesk says its AI agents connect interactions across voice, digital, email and web, and describes Autopilot as resolving requests across voice and digital channels. _(Vendor-reported, checked 20 Sept 2026; source: [Talkdesk AI Agents / Multi-Agent Orchestration](https://www.talkdesk.com/contact-center-platform/ai-agents/); claim id: `talkdesk-cmp-channels`)_

### Yellow.ai — Vendor-documented

- An Escalate to Agent tool places chat conversations in Inbox queues with configurable priority and assignment and delivers a conversation summary to the human agent, plus a Transfer Call tool for PSTN forwarding or SIP transfer on voice. _(Vendor-reported, checked 20 Sept 2026; source: [Escalation (Yellow.ai docs)](https://docs.yellow.ai/docs/nexus/build/tools/escalation); claim id: `yellow-ai-cmp-handoff`)_

### Zendesk AI Agents — Vendor-documented

- Zendesk advertises web, mobile, social, email, and voice. Check channel-specific documentation and availability for the selected agent. _(Vendor-reported, checked 20 Sept 2026; source: [Zendesk AI Agents product overview](https://www.zendesk.com/service/ai/ai-agents/); claim id: `zendesk-cmp-channels`)_

Method: https://ai-agent.review/methodology#shortlists