AI voice agents hold spoken conversations—authenticating callers, resolving intents, invoking tools, and escalating to humans. US contact centers and product teams buy them to contain volume or automate outbound/collections-style flows with governance.
Score latency/voice quality, tool-calling reliability, barge-in, analytics, and enterprise controls (PII, recording, redaction). Builder platforms and enterprise CX suites are different buys.
Fit map: PolyAI and enterprise CX AI for branded containment; Cognigy/NICE-aligned stacks for suite buyers; Bland/Retell/Vapi/Synthflow for fast builder iteration; horizontal CCaaS AI when you want vendor consolidation.
Shortlist below, then pressure-test tool calls on messy utterances. For lighter SMB answering, see AI answering services.
Browse 12 providers
Filter by team size or budget. Each card includes starting price (or Custom when list pricing is unpublished), highlights, pros and cons, and a full profile drawer.
PolyAI
Enterprise Voice AI
Enterprise conversational voice AI for contact centers.
★
4.3 (scores from published listings)
Starting price
Custom
enterprise quote
Best for
Enterprise contact center automation
Voice AI platform used by large brands for natural inbound automation and containment.
Retell AI: Product/CX engineers optimizing for latency and control.
Cresta: Contact centers that need agent assist before full autonomy.
Synthflow: Ops teams wanting no-code agents without an ML staff.
Pricing caveats
Enterprise voice AI is typically Custom; builder platforms are usage-priced per minute plus model/telephony costs. Include evaluation, red teaming, and integration services in TCO. Unpublished list prices should be marked Custom—never invent review counts.
Published plan pricing
These figures are verified by our editorial team. Prices below reflect the plans we track, not introductory marketing rates. Always confirm taxes, regulatory recovery fees, and add-ons on the quote.
Provider
Starting Price
Plans on File
PolyAI
Custom enterprise quote
Usage / Custom: Custom
Bland AI
Usage per minute class
Usage / Custom: Custom
Retell AI
Usage per minute class
Usage / Custom: Custom
Vapi
Usage per minute / platform
Usage / Custom: Custom
NICE Cognigy
Custom enterprise quote
Usage / Custom: Custom
Synthflow
Custom per mo / usage
Usage / Custom: Custom
Replicant
Custom enterprise quote
Usage / Custom: Custom
Sierra
Custom enterprise quote
Usage / Custom: Custom
Kore.ai
Custom enterprise quote
Usage / Custom: Custom
Cresta
Custom enterprise quote
Usage / Custom: Custom
ElevenLabs Agents
Usage usage / platform
Usage / Custom: Custom
Telnyx Voice AI
Usage per minute class
Usage / Custom: Custom
Scenario verdicts
Your situation
Start here
Why
Already standardized on NICE
NICE Cognigy
Portfolio alignment
Enterprise governance
Omni voice/chat
Startup shipping phone agents this quarter
Bland AI
Builder speed
API-first
Usage economics
Composable model strategy
Vapi
Stack flexibility
Model choice
Engineer control
On Telnyx trunks already
Telnyx Voice AI
Network adjacency
Unified vendor
Developer platform
Five capabilities that change buying outcomes
Pressure-test these on your shortlist—what each capability does, and the buyer outcome it unlocks.
Low-latency turn-taking & barge-in
Agents must respond quickly and handle interruptions without talking over callers. Latency kills containment.
Buyer outcome: measure perceived lag in live PSTN tests, not only lab demos.
Reliable tool calling & systems access
Value comes from doing work—lookups, updates, payments—not chatting. Brittle tool calls create silent failures.
Buyer outcome: script failure modes and human fallback for every tool path.
Identity, auth, and PII handling
Voice agents often collect account data. You need authentication patterns, redaction, and retention controls.
Buyer outcome: put security/compliance review on the critical path before production traffic.
Analytics, QA, and continuous improvement
Containment without transcripts/QA is a black box. Supervisors need utterance-level review and regression tests.
Buyer outcome: require analytics access equal to your human QA standard.
Omni handoff to human agents
When AI fails, context must reach a human with the full conversation—not “please hold for a representative.”
Buyer outcome: test warm transfer into your real CCaaS/CRM desktop.
Frequently asked questions
How do AI voice agents differ from IVR?
Traditional IVR steers callers through menus and limited directed dialogs. AI voice agents attempt open natural language understanding, multi-turn state, and tool use.
Hybrid designs still use IVR for authentication then hand to AI—or the reverse. Do not assume 'AI' means zero structure; constrained dialogs often perform better.
Judge systems on task completion, not on whether they sound chatty.
What containment rate is realistic?
It depends on intent mix. Password resets and store hours contain far higher than nuanced billing disputes. Vendors quoting ultra-high containment without your call taxonomy are selling hope.
Establish a baseline with human QA labels, then set staged targets. Improve intents iteratively.
Always measure post-transfer CSAT—forcing containment can backfire.
Build on Bland/Retell/Vapi or buy PolyAI/Cognigy?
Builder platforms optimize for speed and customization when you have engineers. Enterprise platforms optimize for governance, services, and contact-center operating models.
Many firms prototype on builder stacks then re-platform—or vice versa—based on security findings. Be honest about your staffing.
Score total cost including engineers, not only vendor MRR.
Should we start with agent assist instead?
Often yes. Cresta-class assist improves human outcomes with less customer-facing risk while you learn intents from real transcripts.
Assist data frequently informs which workflows are safe to automate next. Autonomy can follow once QA loops exist.
If leadership demands full automation day one, still keep a human escape hatch and a rollback plan.
How do we handle outbound voice agents ethically?
Outbound automation faces TCPA, consent, and brand risks. Ensure calling consent, time-of-day rules, and immediate opt-out. Legal review is mandatory.
Start with low-risk transactional reminders before sales prospecting. Record and retain according to policy.
Providers supply tools; you own the compliance program.
What does a responsible POC look like?
Narrow intent set, production telephony path, evaluation set of real utterances, success metrics, security questionnaire, and a go/no-go date.
Include adversarial tests—interruptions, accents, silence, angry callers. Demo scripts alone are insufficient.
Fund the POC like a project, not a side quest for one enthusiast.
How should voice agents integrate with our CCaaS?
Common patterns: AI in front of the queue for containment; AI as a skill inside the queue; or AI assist beside agents. Each pattern changes licensing and reporting.
Align disposition codes and recording ownership early so analytics remain trustworthy.
See /compare/call-center for platform context and this page for agent layers.
What ongoing costs do buyers forget?
Telephony minutes, LLM/model usage, observability tools, prompt/ops staffing, transcript storage, and red-team testing. Enterprise success packages also recur.
Budget for continuous improvement—static agents decay as products and policies change.
Mark unknown commercial lines as Custom until the quote arrives; do not invent figures.
