# Assistable vs Retell AI

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 at $0.07/min all-in.

- **Assistable:** Assistable is an operating platform, not a parts catalog. Telephony, contacts, campaigns, channels, and QA run on one data plane with one price: voice at $0.07/min all-in 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:** 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.

## 01. Time to first live call

**Assistable:** Signup builds your first assistant for you, grants $10 in usage credit, and sells you a real US or Canadian local number in-app. There is no SDK to integrate and no STT, TTS, or LLM providers to wire together, so the first live call happens in minutes, in one sitting. Full production rollouts land in 2-3 days.

- First assistant created automatically during onboarding
- $10 usage credit granted at signup, pay as you go
- US and Canadian local numbers purchased in-app
- Full production rollouts in 2-3 days

**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.

## 02. Infrastructure and telephony

**Assistable:** Numbers, SIP, recordings, and call control run on the platform's own carrier-grade voice stack, so there is no carrier account to create and no per-component bill to reconcile. 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.

- 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
- <500 ms latency, 99.99% uptime SLA

**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.

## 03. Version control and rollback

**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.

- 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

**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.

## 04. Call routing and transfers

**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.

- 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

**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.

## 05. Outbound at scale

**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.

- 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

**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.

## 06. Observability and QA

**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. There is no per-minute analysis fee; pricing carries no per-feature add-ons.

- 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

**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.

## Side by side

### Getting live

| | Assistable | Retell |
| --- | --- | --- |
| First live call | Minutes, in one sitting | About 15 minutes, per their docs |
| First agent | Built for you at signup | Create from a template |
| Included at signup | $10 credit and a free local number | $10 free credits |

### Platform scope

| | Assistable | Retell |
| --- | --- | --- |
| Versioning with rollback | Yes | Yes |
| Campaign engine | Dial engine with A/B splits, retries, windows | Batch Call: CSV upload, $0.005/dial |
| QA coverage | Every call and chat judged | Sampled calls, paid add-on |
| Channels on one data plane | Voice, SMS, WhatsApp, chat | Voice core; SMS and chat via Twilio numbers and API |

### Telephony

| | Assistable | Retell |
| --- | --- | --- |
| Buy numbers in-app | US local and toll-free, by area code or city | US and Canada, $2/mo local, $5/mo toll-free |
| Bring your own numbers | TLS SIP trunk auto-provisioned per number | Elastic SIP trunking, no telephony charge |
| Warm transfer | Yes | Yes |

### Pricing

| | Assistable | Retell |
| --- | --- | --- |
| Voice per minute | $0.07/min all-in | $0.07 to $0.31/min, their published range |
| Platform and seat fees | None | $0 platform fee on pay as you go |
| Concurrency | No per-line concurrency fees | 20 included, $8/mo each additional, burst surcharge $0.10/min |
| Messaging | Messages $0.02 each | Chat $0.026 to $0.052 per AI message by model |

## 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.

## FAQ

**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 at $0.07/min all-in.

**Is Assistable or Retell more cost effective?**

Assistable is usage-based at $0.07 per minute for voice, all-in, and $0.02 per message, with no platform fee, no seat fees, and free pay-as-you-go signup. Retell's published pricing model is per-component PAYG. Assistable bundles telephony, model, and voice into one per-minute rate, so there are no per-component add-ons to reconcile.

**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?**

Signup is self-serve. Onboarding creates your first assistant, grants $10 in usage credit, and lets you buy a US or Canadian local number in-app, so the first live call happens in minutes without a sales call. Full production rollouts run 2-3 days.

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Source: https://www.assistable.ai/compare/retell