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Comparison · Retell

Assistable vs Retell

Retell gives engineering teams a capable API and honest per-component pricing for building voice agents. Assistable ships the finished operation: telephony, campaigns, contacts, and QA on one platform with published voice rates.

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The bottom line

Assistable

Assistable is an operating platform, not a parts catalog. Telephony, contacts, campaigns, channels, and QA run on one data plane with published voice usage rates and messages at $0.02 each. You publish immutable versions, roll back with one click, and run outbound through a compliance-gated dial engine without assembling any of it.

Retell AI

Retell is a developer-first API and platform. You choose the LLM, the TTS tier, the telephony path, and the add-ons, and each is a published per-minute line item. That gives engineering teams real control, and it also means the surrounding operation, CRM actions, chat surfaces, SMS registration, and campaign hygiene, is yours to build and run.

The real comparison

Six places the platforms actually differ.

The same six questions on every comparison page. Here is how Assistable and Retell each answer them.

01 / 06

Time to first live call

The work and review needed before an agent takes live calls.

Assistable

Start with the workflow, call volume and business outcome you need. Assistable scopes the agent, integrations and handoffs with your team, then agrees on pilot goals, testing and rollout. The platform brings telephony, contacts and campaigns together; production timing depends on the deployment scope and review requirements.

Retell

Retell's self-serve path is genuinely fast: create an agent from a template, test it in a browser call, buy a number, and bind it, about 15 minutes per their docs. From there the build is componentized: the LLM, the TTS tier, and each add-on you enable is a separate priced line item, and back-office actions run through custom tools and webhooks you write.

Assistable delivers

Workflow and integration planning·Pilot goals and success criteria·Testing and rollout plan agreed with your team·Security and data requirements reviewed before rollout

02 / 06

Infrastructure and telephony

What you assemble before production, and who runs it.

Assistable

Numbers, SIP, recordings, and call control run on the platform's own carrier-grade voice stack, with usage components listed on the published rate card. Compliance rails are built in: DNC scrubbing, honeypot detection, A2P 10DLC registration, and KYC review. Web chat, SMS, and voice share one gateway, and identity resolution maps every phone number, email, and web visitor to one contact before the agent runs.

Retell

Retell sells managed US and Canada numbers at $2/mo local and $5/mo toll-free, or you bring your own elastic SIP trunk from Twilio, Vonage, and other carriers with no Retell telephony charge. Voice infrastructure is its own $0.055/min line item. SMS runs on Twilio-backed numbers only, and A2P registration is an approval you file yourself, roughly 2-3 weeks per their docs.

Assistable delivers

TLS SIP trunk auto-provisioned per imported number, SRTP as opt-in·DNC scrubbing, honeypot detection, A2P 10DLC registration, KYC built in·Durable outbox retries from 30 seconds to 1 hour, 5 attempts default

03 / 06

Version control and rollback

How changes ship, and how fast you can undo one.

Assistable

Publishing writes an immutable numbered version to an append-only commit log while live traffic keeps executing the last published version, never the open draft. Traffic follows an explicit deploy pointer, so rollback is one click to any prior version. Branches stage bigger rewrites and merge into Main without changing the flow id, so phone numbers, endpoints, and channels never re-point. Publish is a role-based permission, and every publish and rollback is audit-logged.

Retell

Retell's versioning is real and well documented: published versions are immutable, multiple drafts can coexist, and prod and staging environment tags redeploy instantly when you move a tag. Side-by-side version comparison and a full versioning API round it out. Rollback means re-publishing a prior version as a new draft or moving a tag back.

Assistable delivers

Immutable numbered versions in an append-only commit log·Explicit deploy pointer with one-click rollback·Branches merge into Main without changing the flow id·Publish gated by role-based permission, audit-logged·Test drawer shows node, model, tokens, latency, and cost per reply

04 / 06

Call routing and transfers

What happens when a caller needs a human.

Assistable

Warm transfer is one configuration, not flow wiring: it holds the caller on hold music, dials your team in order with fallback hunting, screens each leg with answering-machine detection so voicemail never gets the call, and whispers a private briefing generated from the live transcript before bridging. Unanswered transfers can resume the AI instead of hanging up, and a per-minute sweep force-resolves stale holds. Tag rules route inbound by contact tag with priority and active hours.

Retell

Retell documents cold, warm, and agentic warm transfers, where a second AI talks to the human target and decides whether to bridge, with whisper messages, three-way announce, and human detection with a timeout. Transfer failure routes to a failure edge in your flow. When concurrency is maxed, inbound calls queue about 40 seconds, then go to a single configured fallback number or end.

Assistable delivers

Ordered fallback hunting, up to 6 dial attempts, 25-second default ring timeout·Answering-machine detection screens every transfer leg·Whisper briefing generated by the LLM from the live transcript·Connected, voicemail, no-answer, and failed each route their own branch·Tag rules with priority and active hours for time-of-day routing

05 / 06

Outbound at scale

Dialing a list without burning it.

Assistable

Campaigns are an engine, not a CSV upload. A dial engine converges every minute, tops running campaigns up to their concurrency caps, and reconciles outcomes seconds after hangup. A/B splits across assistants are built in, retries for no-answer, busy, and failed honor the calling window, and every dial passes DND, blacklist, E.164, and wallet checks, with a wallet at zero pausing the campaign instead of burning the list.

Retell

Batch Call is first-class in Retell: upload a CSV with a phone number column, extra columns become dynamic variables, then send now or schedule inside configurable time windows, at $0.005 per dial on top of the per-minute rate. A per-row agent-version override column makes manual split tests possible. Structurally, the list you upload is the campaign: enrollment, variables, and splits are columns in the CSV you prepare.

Assistable delivers

Dial engine converges every minute; claim-first updates make double-dials impossible·A/B splits must sum to 100; deficit-based assignment converges on the split·Timezone-aware windows with day-of-week selection and overnight wrap·Wallet at zero pauses the campaign with a stated reason·Enroll up to 25,000 contacts by filter, list, or CSV

06 / 06

Observability and QA

How you find out something went wrong.

Assistable

Write monitor rules in plain English and an LLM judge grades every finished call and chat, not a sample, with verdicts citing the decisive transcript moment. When a rule fires, the AI drafts a minimal prompt fix, shows a line diff, and proves it by replaying the failing conversation 3 times through the published flow, so confidence is a measured pass rate, never self-reported. Observation is billed per observer, per call. PII removal and knowledge-base usage are also itemized when enabled or used; see the current rate card.

Retell

Retell's QA stack is productized: automatic post-call analysis with user-defined extraction fields, simulation testing with AI-simulated users before release, and an AI QA add-on that evaluates a sampled set of calls across hallucination, knowledge base accuracy, latency, sentiment, and tool usage. AI QA is priced at $0.10 per analyzed minute after the first 100 free.

Assistable delivers

LLM judge grades every finished call and chat, not a sample·Verdicts cite the decisive transcript moment with confidence·Fixes proven by replaying the failing conversation 3 times through the published flow·Per-rule health: fire rate, drift, silence, human-overturn rate

At a glance

Side by side

Getting live

First live call
AssistableTimeline agreed to deployment scope
RetellAbout 15 minutes, per their docs
First agent
AssistableDefined around your workflow and pilot
RetellCreate from a template
Included at signup
AssistablePilot scope agreed in your proposal
Retell$10 free credits

Platform scope

Versioning with rollback
AssistableYes
RetellYes
Campaign engine
AssistableDial engine with A/B splits, retries, windows
RetellBatch Call: CSV upload, $0.005/dial
QA coverage
AssistableEvery call and chat judged
RetellSampled calls, paid add-on
Channels on one data plane
AssistableVoice, SMS, WhatsApp, chat
RetellVoice core; SMS and chat via Twilio numbers and API

Telephony

Buy numbers in-app
AssistableUS local and toll-free, by area code or city
RetellUS and Canada, $2/mo local, $5/mo toll-free
Bring your own numbers
AssistableTLS SIP trunk auto-provisioned per number
RetellElastic SIP trunking, no telephony charge
Warm transfer
AssistableYes
RetellYes

Pricing

Voice per minute
Assistablepublished voice rates
Retell$0.07 to $0.31/min, their published range
Platform and seat fees
AssistableAccount and seat scope agreed in your proposal
Retell$0 platform fee on pay as you go
Concurrency
AssistableNo per-line concurrency fees
Retell20 included, $8/mo each additional, burst surcharge $0.10/min
Messaging
AssistableMessages $0.02 each
RetellChat $0.026 to $0.052 per AI message by model

Retell AI capabilities and pricing reflect their publicly published information as of July 2026 and may change.

Why teams switch

Why teams choose Assistable.

01

A deployment built around your operation

Start with your workflows, volume and business goals. Agree on integration scope, pilot success criteria, testing and rollout with our team. Timing and support are set out in your proposal.

02

Version control for agents

Immutable numbered versions in an append-only history, an explicit deploy pointer with one-click rollback, and branches that merge without changing the flow id. Live traffic never executes an open draft.

03

Telephony that behaves like a phone system

Ordered team hunting with answering-machine detection, whisper briefings generated from the live transcript, tag rules with active hours, and DND, blacklist, and wallet gates on every outbound dial.

Under the hood

The infrastructure
most platforms rent.

We operate dedicated network, telephony, and compliance rails, and let you choose the models on top. That is what keeps conversations fast, clear, and safe at scale.

  • Edge

    Co-located edge PoPs and GPUs power low-latency voice AI globally.

  • Telephony

    A full telephony stack built in: native calling and texting without wiring a carrier.

  • Network

    Audio runs on a private global network, bypassing the public internet for call quality.

  • Compliance

    A programmatic compliance layer: DNC and honeypot detection, 10DLC and KYC, attribution reporting.

  • Models

    LLM, TTS, and STT à la carte, self-hosted or from major providers. Enterprises can bring their own keys.

  • Languages

    100+ languages and dialects, with real-time multilingual transcription and translation.

  • Coverage

    Calling and texting in 105+ countries.

Questions

Assistable vs Retell, answered.

What is the difference between Assistable and Retell?
Retell gives engineering teams a capable API and honest per-component pricing for building voice agents. Assistable ships the finished operation: telephony, campaigns, contacts, and QA on one platform with published voice rates.
Is Assistable or Retell more cost effective?
Assistable plans start with quarterly commitments scoped to your deployment, with usage charged separately. Voice charges depend on orchestration, TTS, the language model, applicable telephony and enabled add-ons; chat starts at $0.02 per AI message. See /pricing for the current rate card and any announced changes. Retell's published pricing model is per-component PAYG. The rate card explains the voice base and any additional charges for the providers and options you choose.
When should I choose Retell over Assistable?
Retell is the right call when you have an engineering team that wants API-level control of every layer. Its versioning story is genuinely strong: immutable published versions, parallel drafts, and prod and staging environment tags that redeploy the moment you move a tag. Per-component pricing lets you tune each line item, down to bringing your own SIP trunk at no Retell telephony charge, and you get LLM choice across OpenAI, Anthropic, and Gemini plus simulation testing before release. If you are building a custom voice product on top of an API, with your own chat surfaces, CRM actions, and campaign tooling around it, Retell is a solid foundation, and its enterprise tier adds SSO, dedicated servers, and on-prem options.
How fast can I get a live AI agent with Assistable?
Talk to sales about your workflow, expected volume and integration needs. Together we define pilot goals, testing and a rollout plan. Production timing is agreed around the deployment scope and your technical, security and procurement reviews.

Fair is fair

When Retell is the right call

Retell is the right call when you have an engineering team that wants API-level control of every layer. Its versioning story is genuinely strong: immutable published versions, parallel drafts, and prod and staging environment tags that redeploy the moment you move a tag. Per-component pricing lets you tune each line item, down to bringing your own SIP trunk at no Retell telephony charge, and you get LLM choice across OpenAI, Anthropic, and Gemini plus simulation testing before release. If you are building a custom voice product on top of an API, with your own chat surfaces, CRM actions, and campaign tooling around it, Retell is a solid foundation, and its enterprise tier adds SSO, dedicated servers, and on-prem options.

“After 18 months testing voice AI platforms including Bland.ai and Synthflow.ai… Assistable delivered flawlessly on over 25,000 calls in recent weeks.”
Maurice M.Assistable customer

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