Retell AI Alternatives for Enterprise Voice Agents: A Shunya Comparison

Retell AI is a realtime voice-agent platform built around phone conversations, with tools for agent creation, testing, telephony, knowledge bases, call analytics, webhooks, and integrations. Its current platform supports both inbound and outbound calls, and Retell describes its system as handling roughly 600 ms end-to-end latency with proprietary turn-taking.

Shunya approaches enterprise voice agents from a broader speech and intelligence architecture.

Its Voice Agent platform combines speech recognition, knowledge-grounded reasoning, TTS, enterprise workflows and telephony, with the conversation moving through five stages: Listen, Ground, Decide, Translate and Speak. Shunya currently documents <1.5 seconds end-to-end voice-to-voice response, 216+ language speech recognition, and deployment across cloud, private VPC, on-premise and edge.

Both platforms are designed for production voice conversations.

The important difference is what sits around the conversation.

Retell is strongly focused on the realtime voice-agent layer. Shunya combines that layer with enterprise speech, knowledge grounding, business intelligence and deployment infrastructure.

For companies evaluating Retell AI alternatives, this comparison looks at the factors that matter in production: architecture, latency, turn-taking, knowledge grounding, task execution, multilingual speech, telephony, integrations, analytics, security, deployment and total cost.

What is Retell AI?

Retell AI is designed around a simple idea:

Build an AI agent that can actually hold a phone conversation.

Its current platform covers:

Agent building

Inbound calling

Outbound calling

Knowledge bases

Call analytics

Simulation testing

Webhooks

API access

Telephony

and integrations with enterprise systems.

Retell also supports use cases such as:

Customer support

AI receptionists

Appointment booking

Sales qualification

Banking

Insurance

and other phone-based workflows.

The platform is deliberately centered on voice conversations, rather than being a general-purpose enterprise AI platform with voice added as one feature.

How Shunya approaches voice agents

Shunya’s architecture starts one layer deeper.

The platform combines:

Speech-to-Text

↓

Knowledge-grounded reasoning

↓

Text-to-Speech

and wraps that into a voice-agent workflow. Shunya describes the call lifecycle as:

Listen

→ Ground

→ Decide

→ Translate

→ Speak.

This means the agent isn’t only responsible for understanding the customer’s words.

It also needs to understand:

What the business knows

What the business allows

What the customer is asking

What action should happen next

That architecture is especially relevant when the agent needs to work with enterprise systems and business rules, rather than simply answer questions.

Voice-agent architecture: the important comparison

Retell gives developers flexibility over the underlying components.

Its current platform supports different LLM providers, TTS providers and telephony options, including the ability to bring your own components.

This is useful for teams that want to assemble a voice stack around preferred providers.

A typical architecture can therefore look like:

Telephony → Retell orchestration → LLM / TTS / tools

Shunya is more vertically integrated around speech and enterprise intelligence:

Telephony / Audio

↓

STT

↓

Enterprise knowledge + SOPs + business rules

↓

Reasoning

↓

Tools / enterprise systems

↓

TTS

↓

Customer

Shunya’s platform also exposes the underlying speech and intelligence layers separately.

For developers, this creates a meaningful architectural choice:

Do you want to orchestrate providers?

or:

Do you want an integrated speech + intelligence platform with enterprise grounding built into the voice-agent architecture?

Realtime latency and turn-taking

Retell puts realtime conversation at the center of its product.

The company currently reports approximately 600 ms end-to-end latency, with proprietary turn-taking designed to reduce conversational dead air and handle interruptions naturally.

Retell also describes its agents as handling:

Barge-in

Interruptions

Natural turn-taking

and realtime phone conversations.

Shunya documents <1.5 seconds end-to-end voice-to-voice response, with a published pipeline breakdown of roughly:

300 ms ASR

100 ms translation

400 ms synthesis

with additional headroom for the rest of the pipeline.

These measurements should not be treated as identical benchmarks.

Retell’s ~600 ms figure and Shunya’s <1.5 s figure refer to vendor-defined measurement environments and architectures.

A proper enterprise test should measure:

User stops speaking

→ speech recognition

→ reasoning

→ knowledge retrieval

→ tool execution

→ TTS

→ first audible response

That is the metric the customer actually experiences.

Conversation quality is more than low latency

A voice agent can be fast and still feel unnatural.

Real conversations contain:

Interruptions

Corrections

Follow-up questions

Ambiguous requests

Incomplete sentences

Silence

Background noise

Retell’s current platform places strong emphasis on proprietary turn-taking and interruption handling.

Shunya’s architecture adds another dimension: context grounded in enterprise knowledge and business rules.

That creates two different aspects of conversation quality.

Conversational responsiveness

Can the agent listen, stop, respond and continue naturally?

Business correctness

Does the response remain consistent with the organization’s actual knowledge and policies?

For enterprise deployments, both matter.

A customer should not have to wait several seconds for an answer.

But a fast wrong answer is still a bad customer experience.

Knowledge bases versus deeper enterprise grounding

Retell provides a built-in Knowledge Base that can be used to provide information to agents. Its current pricing also lists Knowledge Base as an agent add-on, with the first 10 knowledge bases included in pay-as-you-go access.

Retell’s current examples show agents using connected knowledge sources to answer questions from company information and policies.

Shunya goes further into the architecture by explicitly grounding responses in:

Knowledge graphs

SOPs

Business rules

and enterprise systems.

The difference becomes important when the customer asks something that requires a policy decision.

For example:

“Can you waive my late payment fee?”

The agent shouldn’t invent an answer.

It should determine:

What policy applies

Whether this customer qualifies

What information needs to be checked

Whether the action is permitted

Whether a human needs to approve it

This is where grounding and workflow logic become part of voice-agent quality.

From answering questions to completing tasks

Enterprise voice agents are ultimately judged by what they accomplish.

Consider:

“I need to reschedule my appointment.”

A useful agent may need to:

Identify the customer

→ Retrieve the appointment

→ Check availability

→ Update the booking

→ Confirm the new time

Retell supports tools, webhooks and integrations that allow agents to interact with external systems. Its platform also supports call transfers and actions during conversations.

Shunya’s Voice Agent platform similarly connects agents to existing systems and documents workflows such as:

KYC verification

Appointment booking

Payment reminders

Customer support.

For production evaluation, the important metric is therefore:

Task completion rate

not just:

Conversation success rate

A voice agent that gives a convincing explanation but fails to complete the requested task has not really solved the customer’s problem.

Multilingual voice agents

Retell supports multilingual voice applications, and its current platform allows teams to choose from multiple voice and language configurations. Its pricing page also supports voices from providers such as MiniMax, ElevenLabs, Cartesia and OpenAI, alongside Retell’s own voices.

Shunya approaches multilingual voice as a core part of the speech architecture.

Its TTS stack covers global, Asian and 23 Indic languages, with 46 documented voices across 23 Indic languages plus English, while the Voice Agent platform uses 216+ language ASR.

This is particularly important for India.

A real call may move between:

Hindi

English

Hinglish

and regional terminology in a single conversation.

A production benchmark should therefore test:

Language switching

Names

Numbers

Currency

Regional pronunciation

Code-switching

rather than simply checking whether a language appears on a supported-language list.

Global, Asian and Indic voice identity

Shunya’s TTS architecture is built around multilingual voice identity, where a voice can be used across supported languages.

That matters for enterprise brands that want a recognizable voice across markets.

For example:

English customer support

→ Hindi customer support

→ Japanese customer support

should not necessarily sound like three completely different assistants.

Shunya’s broader voice stack is designed around global, Asian and Indic voice experiences, with cross-lingual synthesis as part of its TTS architecture.

Retell, meanwhile, lets teams choose among its own voices and external providers, including MiniMax, Fish, ElevenLabs, Cartesia and OpenAI.

This creates an important distinction:

Retell gives you provider flexibility.

Shunya provides an integrated multilingual speech architecture.

Telephony is central to both platforms

Retell is explicitly phone-first.

Its platform supports:

Inbound calls

Outbound calls

SIP

Telephony providers

Call transfers

IVR navigation

Phone numbers

and realtime call workflows.

Retell can also navigate external IVRs by sending DTMF digits, which is useful for outbound agents calling other businesses or automated systems.

Shunya also integrates with enterprise telephony systems including:

Cisco

Avaya

Exotel

Knowlarity.

Its speech stack supports telephony-oriented audio formats including μ-law and A-law.

For a contact center, the best evaluation is not a browser demo.

Test the actual:

Telephony provider

Codec

Call routing

Barge-in

Transfer

Recording

Network conditions

and concurrency.

Integrations and enterprise actions

Retell supports a broad range of integrations and provides webhooks and API access for connecting agents to business systems.

Its current use-case materials highlight integrations with systems such as:

Salesforce

Avaya

Genesys

Amazon Connect

Telnyx

and other business tools.

Shunya provides documented integrations across:

CRM: Salesforce, Zoho, HubSpot, Google Sheets

Telephony: Cisco, Avaya, Exotel, Knowlarity

E-commerce: Shopify, WooCommerce, Odoo

Messaging: WhatsApp, LINE, KakaoTalk.

The more important question is what the agent can do with those integrations.

For example:

Customer asks for an order update → agent checks the order → explains the status → changes the delivery slot → confirms the update.

That is a meaningful production workflow.

Analytics, testing and quality assurance

Retell includes call analytics, transcripts and simulation testing as part of its platform. Its enterprise offering also includes features such as AI quality assurance, safety guardrails and PII removal.

Retell also describes post-call analysis around sentiment, outcomes, first-call resolution and transfers.

Shunya’s platform includes an observability and evaluation layer designed to test agents before deployment and evaluate live production calls. It also provides transcript-level intelligence such as intent, sentiment, diarization and summarization.

For enterprise deployments, this should be treated as a continuous loop:

Build

→ Simulate

→ Deploy

→ Measure

→ Find failures

→ Improve

→ Re-test

The quality of an enterprise voice agent should improve based on actual calls rather than being frozen after launch.

Security and deployment

Retell’s current enterprise offering includes:

Custom MSA/DPA terms

Role-based access control

Custom SSO

Dedicated stable servers

High concurrency

24/7 support.

Retell also lists security and compliance capabilities including SOC 2, HIPAA and GDPR readiness, along with optional PII redaction.

Shunya offers a different deployment range:

Cloud

Private VPC

On-premise

Edge.

Shunya’s deployment documentation describes container parity between cloud and self-hosted environments, with the same core Triton-based deployment architecture available inside a customer’s VPC or data center.

This gives enterprise architects another important decision:

Managed voice-agent infrastructure

versus

the ability to control where the speech and intelligence stack runs.

Pricing

Retell currently publishes transparent pay-as-you-go pricing.

The current range for AI Voice Agents is:

$0.07–$0.31 per minute

with enterprise pricing available for larger deployments. Retell includes 20 concurrent calls, free credits for new accounts, and access to features such as analytics, simulation testing, webhooks and knowledge bases.

However, the headline per-minute number is not the full cost.

Retell’s own pricing breakdown separates:

LLM

Voice infrastructure

TTS

Telephony

Knowledge Base

Denoising

Safety guardrails

PII removal

AI QA

among other components.

Shunya currently lists Meera Voice Agents at $0.0526 per minute, with STT, LLM reasoning, TTS, turn-taking, barge-in and orchestration included in the published rate.

That creates a fundamentally different pricing model.

Retell: modular component pricing.

Shunya: all-inclusive per-minute voice-agent pricing.

For an enterprise comparison, calculate:

Cost per minute

Cost per connected call

Cost per completed task

Cost at peak concurrency

Cost including telephony

Cost including enterprise deployment

The most useful metric is the total cost of a successful customer interaction.

Where Retell AI fits

Retell is particularly relevant when you need:

Realtime phone agents

Its platform is built around inbound and outbound phone conversations.

Low-latency conversations

Retell currently reports roughly 600 ms end-to-end latency with proprietary turn-taking.

Provider flexibility

Teams can use Retell’s own components or bring their own LLM, voice engine and SIP telephony.

Agent testing

Simulation testing and call analytics are included in the current platform.

Inbound and outbound automation

Retell supports support, sales, reception, appointment and other phone-based workflows.

Fast deployment

Retell’s product is designed to let teams build and deploy phone agents without assembling the entire realtime voice infrastructure themselves.

Where Shunya fits

Shunya is particularly relevant when the voice agent needs to become part of the enterprise’s intelligence architecture.

Knowledge-grounded responses

Responses can be grounded in knowledge graphs, SOPs and business rules.

Enterprise actions

Agents can connect to systems to support workflows such as KYC, appointment booking, payment reminders and customer support.

Global, Asian and 23 Indic languages

The voice stack combines global, Asian and 23 Indic language applications, with 46 documented TTS voices across 23 Indic languages plus English and 216+ language ASR.

Integrated speech stack

STT, TTS, intelligence and voice agents are part of one platform rather than separate products that have to be assembled.

Flexible deployment

Shunya supports cloud, Private VPC, on-premise and edge deployment models.

Enterprise speech infrastructure

The same platform extends beyond voice agents into speech recognition, TTS, speech intelligence and custom models.

Retell AI and Shunya by use case

Use case	Retell AI	Shunya
Inbound phone support	Strong fit	Strong fit
Outbound calling	Strong fit	Strong fit
Appointment booking	Strong fit	Strong fit
AI receptionist	Strong fit	Supported
Sales qualification	Strong fit	Supported
Contact center automation	Strong fit	Core use case
BFSI workflows	Strong fit	Core use case
Healthcare workflows	Supported	Core use case
Global voice agents	Supported	Strong fit
Asian voice applications	Provider-dependent	Strong fit
Indic voice applications	Provider-dependent	Core capability
Hindi / Hinglish	Supported	Strong fit
Enterprise knowledge grounding	Knowledge Base	Knowledge graph + SOP + business rules
Task automation	Tools / integrations	Tools / enterprise systems
BYO LLM / TTS	Yes	More integrated stack
Telephony	Core	Core
Analytics	Core	Core
Simulation / evaluation	Yes	Yes
Cloud deployment	Yes	Yes
Private VPC	Enterprise	Yes
On-premise	Enterprise-dependent	Yes
Edge	Not a primary product focus	Yes
Pricing	Modular per-minute	All-inclusive per-minute

The table summarizes documented capabilities and current product positioning. Actual suitability depends on the specific implementation.

How to benchmark Retell against Shunya

Don’t benchmark voice agents with one scripted conversation.

Build a production test set around the workflows your business actually needs.

For example:

Customer support

Appointment booking

Collections

KYC

Order status

Outbound qualification

Renewals

Fraud alerts

Then include real-world conversational complexity:

Interruptions

Background noise

Hindi-English code-switching

Names

Numbers

Currency

Product codes

Ambiguous requests

Follow-up questions

For each platform, measure:

Speech recognition

Did the agent understand what the customer actually said?

Latency

Measure the complete:

user stops speaking → first audible response

Turn-taking

Does the agent know when to listen, when to speak and when to stop?

Grounding

Does the response reflect the correct enterprise information and policy?

Task completion

Was the requested action actually completed?

Multilingual consistency

Can the customer switch languages without losing context?

Voice quality

Evaluate:

naturalness

pronunciation

prosody

expression

telephony clarity

Human handoff

Does a transferred call carry enough context for the human agent to continue without asking the customer to repeat everything?

Reliability

Test performance at:

low concurrency

normal production concurrency

peak concurrency

Cost

Compare total cost per completed task, not only the headline platform rate.

The real comparison is voice infrastructure versus voice intelligence

Retell and Shunya overlap considerably.

Both can:

make and receive calls

run realtime conversations

connect to business systems

use knowledge

transfer calls

analyze conversations

operate at enterprise scale

The architectural distinction is where they put the center of gravity.

Retell is strongly centered on realtime voice-agent infrastructure and orchestration. It gives developers the flexibility to choose components and provides the telephony, turn-taking, testing and monitoring layer needed to run them in production.

Shunya centers the voice agent around enterprise speech and intelligence.

The agent doesn’t just hear and respond.

It is designed to:

understand speech

ground itself in business knowledge

apply rules

take actions

speak naturally

and run wherever the enterprise needs it to run.

That difference can matter more than a few hundred milliseconds of theoretical latency.

Final words

Retell AI is a mature platform for building realtime phone agents, with a strong focus on turn-taking, telephony, agent testing, integrations, analytics and flexible provider selection. Its current platform reports approximately 600 ms end-to-end latency and supports both inbound and outbound calling.

That makes Retell particularly relevant for teams that want to build and deploy conversational phone agents quickly while retaining control over the underlying LLM, voice and telephony components.

Shunya takes a broader enterprise approach.

Its Voice Agent platform combines STT, knowledge-grounded reasoning and TTS, with responses grounded in knowledge graphs, SOPs and business rules, and enterprise actions connected to existing systems.

Its speech architecture covers global, Asian and 23 Indic languages, while the broader ASR platform supports 216+ languages and multilingual, code-switched conversations.

Shunya also provides cloud, Private VPC, on-premise and edge deployment, which can be important when the same voice-agent architecture needs to serve different security, latency or data-residency requirements.

The right platform therefore depends on the architecture you are trying to build.

For teams primarily looking for a realtime phone-agent orchestration layer, Retell offers a focused platform with strong telephony and developer flexibility.

For teams looking for enterprise voice agents that combine multilingual speech, business knowledge, reasoning, actions and flexible deployment, Shunya provides a more integrated voice-AI architecture.

The most useful evaluation is not a demo comparison.

Take your real customer workflows.

Use your real language mix.

Connect your real CRM.

Run the actual phone calls.

Then measure:

Did the agent understand?

Did it respond naturally?

Did it follow the business rules?

Did it complete the task?

Did it transfer correctly when needed?

Did it remain reliable at production concurrency?

What did the completed interaction actually cost?

That is the difference between choosing a voice-agent demo and choosing a production voice-agent platform.

Frequently asked questions

What is Retell AI?

Retell AI is a platform for building realtime AI voice agents for inbound and outbound phone conversations, with agent building, telephony, knowledge bases, testing, analytics, APIs and integrations.

Is Shunya an alternative to Retell AI?

Yes. Shunya provides enterprise Voice Agents combining STT, knowledge-grounded reasoning and TTS, with enterprise integrations, telephony and flexible deployment options.

How fast is Retell AI?

Retell currently states approximately 600 ms end-to-end latency with proprietary turn-taking. This is a vendor-reported measurement and should be validated against the workload and environment of a production deployment.

How fast is Shunya Voice Agent?

Shunya currently documents less than 1.5 seconds end-to-end voice-to-voice response, with an approximately 300 ms ASR, 100 ms translation and 400 ms synthesis breakdown in its published benchmark.

Does Retell support inbound and outbound calls?

Yes. Retell supports both inbound and outbound AI phone calls.

Does Shunya support inbound and outbound voice agents?

Yes. Shunya provides enterprise voice-agent workflows for customer support, outbound campaigns and other phone-based enterprise use cases.

Does Retell support knowledge bases?

Yes. Retell provides a built-in Knowledge Base capability that agents can use during conversations.

How does Shunya ground voice-agent responses?

Shunya grounds responses in knowledge graphs, SOPs and business rules, alongside connected enterprise data and systems.

Can Retell voice agents take actions?

Yes. Retell provides webhooks, APIs, tools and integrations that can connect agents to external business systems.

Can Shunya voice agents take actions?

Yes. Shunya documents workflows including KYC verification, appointment booking, payment reminders and customer support, connected to enterprise systems.

Does Retell support multilingual voice agents?

Yes. Retell supports multilingual voice configurations and lets customers use voices from multiple providers, including MiniMax, ElevenLabs, Cartesia and OpenAI.

Does Shunya support multilingual voice agents?

Yes. Shunya’s voice stack combines global, Asian and 23 Indic languages, while its ASR platform supports 216+ languages and code-switched speech.

Does Retell support telephony?

Yes. Telephony is a core part of Retell’s voice-agent platform, including phone numbers, SIP, inbound and outbound calls and IVR navigation.

Does Shunya support telephony?

Yes. Shunya supports enterprise telephony integrations including Cisco, Avaya, Exotel and Knowlarity, along with telephony-oriented speech formats.

Can Retell use external TTS and LLM providers?

Yes. Retell’s current platform allows teams to bring their own LLM, voice engine and SIP telephony, while also offering multiple voice providers.

Does Shunya provide an integrated speech stack?

Yes. Shunya combines STT, TTS, speech intelligence and Voice Agents within its broader platform.

Does Retell support enterprise deployment?

Yes. Retell’s Enterprise plan includes a dedicated stable server, custom MSA/DPA terms, SSO, role-based access control and higher concurrency.

Does Shunya support private or on-premise voice agents?

Yes. Shunya supports Private VPC, on-premise and edge deployment alongside managed cloud deployment.

What does Retell AI cost?

Retell currently lists AI Voice Agents at $0.07–$0.31 per minute on pay-as-you-go, with custom Enterprise pricing. Additional costs can apply for LLMs, TTS, telephony and agent add-ons.

What does Shunya Voice Agent cost?

Shunya currently lists Meera Voice Agents at $0.0526 per minute, with STT, LLM reasoning, TTS, turn-taking, barge-in and orchestration included in the published rate.

How should enterprises compare Retell AI alternatives?

Use the same customer workflows, speech samples, languages, knowledge sources, backend systems and telephony environment on each platform. Measure latency, speech accuracy, grounding, task completion, handoff quality, reliability and total cost per completed interaction.