# Assistable vs Vapi

Vapi gives developers an API to assemble a voice agent from the STT, LLM, and TTS providers they choose. Assistable is the operated alternative: telephony, versioning, campaigns, and QA ship built in at $0.07/min all-in.

- **Assistable:** Assistable is an operated platform. Telephony, transfer logic, campaign dialing, version control, and QA grading run inside the product on the platform's own carrier-grade voice stack. You sign up, the platform creates your first assistant during onboarding, you buy a number in-app, publish, and pay $0.07/min all-in with no platform fee and no per-line concurrency fees.
- **Vapi:** Vapi is developer infrastructure. You choose the STT, LLM, and TTS layers per assistant from dozens of providers, import carrier numbers or SIP trunks for production telephony, point webhooks at your own server for dynamic behavior like transfer destinations, and, per their own enterprise best practices, promote configs across separate dev, staging, and prod organizations with Git and CI.

## 01. Time to first live call

**Assistable:** Sign up at platform.assistable.ai and the platform creates your first assistant during onboarding, grants $10 in usage credit, and sells you a real US or Canadian local number in-app. There is no STT, TTS, or LLM provider to wire together and no telephony account to create. First live call happens in minutes, in one sitting, and full production rollouts run 2-3 day deploys.

- First assistant created automatically during onboarding
- Free local phone number plus $10 in calling credit at signup
- US and Canadian local numbers purchasable in-app
- No SDK, no STT/TTS/LLM wiring, no telephony account to create
- 2-3 day deploys for full production rollouts

**Vapi:** Vapi's quickstart has you pick three layers per assistant, STT, LLM, and TTS, from dozens of providers, through the dashboard or SDKs and a CLI. The dashboard path promises a first agent in 5 minutes; a production phone agent still needs provider choices, an imported carrier number or SIP trunk beyond the 10 free US-only numbers, and webhooks on your server for dynamic behavior.

## 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 SIP credentials to manage. Compliance rails are built in: DNC scrubbing, honeypot detection, A2P 10DLC campaign registration, and KYC review. Web chat, SMS, and voice share one channel gateway that resolves every phone number, email, and web visitor to a single contact record, and async sends queue in a durable outbox with retries.

- US local and toll-free numbers searchable by area code or city, answering agent assigned at purchase
- TLS SIP trunk auto-provisioned per imported number, clean rollback on failure
- DNC scrubbing, honeypot detection, and A2P 10DLC registration built in
- Durable outbox: 5 retry attempts backing off 30 seconds to 1 hour
- <500 ms latency, 0.4s median answer, 99.99% uptime SLA

**Vapi:** Vapi hosts the orchestration layer while you select STT, LLM, and TTS providers, or bring your own API keys at zero markup. Free in-app numbers are US-only and capped at 10 per account; production and international numbers come by importing from your carrier or via SIP trunking. Accounts include 10 concurrent call slots by default, with additional lines at $10 per line per month on the Build plan.

## 03. Version control and rollback

**Assistable:** Edits autosave to a working draft while live traffic keeps executing the last published version. Publishing writes an immutable numbered version into an append-only commit log, and an explicit deploy pointer decides which version serves traffic, with one-click rollback to any prior version. Branches stage bigger rewrites and merge into Main without changing the flow id, so phone numbers, endpoints, and channels keep pointing at the same agent. No separate orgs, no Git repo of configs, no CI deployer to build.

- Immutable numbered versions with author, in an append-only commit log
- Explicit deploy pointer with a Live badge, never latest-wins
- One-click rollback: activate any prior version and traffic moves instantly
- Branch merges republish without changing the flow id
- Publish and rollback are role-gated and audit-logged

**Vapi:** Vapi ships assistant version history, a diff preview of unpublished changes against the live version, dashboard revert, and Admin, Editor, and Viewer roles. For dev, staging, and prod, their enterprise best-practices doc recommends separate organizations per environment with configs stored as JSON or YAML in Git and promoted by your CI.

## 04. Call routing and transfers

**Assistable:** Warm transfer holds the caller on hold music, dials your team in order with up to 6 attempts at a 25-second default ring timeout, and screens every leg with answering-machine detection so voicemail never gets the call. The human hears a private briefing, static or generated by the LLM from the live transcript, before bridging; connected, voicemail, no-answer, and failed each route their own flow branch, and unanswered transfers can resume the AI instead of hanging up. Inbound, tag rules bind a contact tag to an assistant per channel with priority and active hours, so time-of-day routing is a setting, not a server you run.

- Ordered fallback hunting: up to 6 dial attempts, 25-second default ring timeout per attempt
- Answering-machine detection screens every transfer leg
- Whisper briefing generated by the LLM from the live call transcript
- Connected, voicemail, no-answer, and failed each route their own branch
- Per-minute sweep force-resolves stale holds so no caller sits in silence

**Vapi:** Vapi transfers to a phone number, SIP URI, or another assistant, with blind transfer plus several warm modes, including an AI-generated summary and a fallback plan that plays a message then hangs up or continues if the transfer fails. Their call-forwarding docs note warm transfer is currently available only with Twilio-based telephony, and dynamic destinations require your server answering a POST to the call's controlUrl.

## 05. Outbound at scale

**Assistable:** The dial engine converges every minute: it starts scheduled campaigns, tops running ones up to their concurrency cap, and marks them complete when the list drains, with claim-first updates that make double-dials impossible. Calling windows are timezone-aware with day-of-week selection and overnight wrap, retries for no-answer, busy, and failed honor the window, and every dial passes DND, blacklist, and E.164 gates. A wallet at zero pauses the campaign with a stated reason instead of burning the list.

- A/B splits across assistants must sum to 100; deficit-based assignment converges on the configured split
- Timezone-aware calling windows with day-of-week selection and overnight wrap
- Per-campaign concurrency and calls-per-minute caps, window-honoring retries
- Wallet at zero pauses the campaign with a stated reason
- Enroll by contact filter up to 25,000 contacts, hand-picked lists, or deduped CSV

**Vapi:** Vapi's Outbound Campaigns take a CSV with a mandatory E.164 number column, an assistant, and a launch click, with extra CSV columns becoming dynamic variables. Campaigns require a number from your own phone provider, not a free Vapi number, and dialing is bounded by org concurrency; overflow calls are queued and retried a few minutes later.

## 06. Observability and QA

**Assistable:** Monitor rules are written in plain English and an LLM judge grades every finished call and chat against them, citing the decisive transcript moment with a confidence score. Alerts arrive with the transcript attached, and repeat failures cluster into issues. When something fails, 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 and re-judging; confidence is the measured pass rate, never self-reported.

- 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 before apply
- Per-rule health: fire rate, drift, silence, human-overturn rate
- Recording, transcript, sentiment, and itemized cost on one call row

**Vapi:** Vapi publishes the deepest testing stack in the category: Evals that validate assistants with mock conversations and exact-match, regex, or AI judges, plus simulations, voice and chat test suites, scorecards, and a monitoring quickstart. Call logs carry duration, outcome, transcripts, and recordings.

## Side by side

### Platform model

| | Assistable | Vapi |
| --- | --- | --- |
| Voice stack | Operated end to end, one vendor | You choose STT, LLM, and TTS per assistant |
| Phone numbers | US local and toll-free bought in-app | 10 free US numbers; import your carrier for production |
| Dynamic call logic | Flow branches in the builder | Your server via webhooks and controlUrl |
| Environments | Branches merge on one flow id | Separate orgs, Git configs, CI promotion |

### Versioning and QA

| | Assistable | Vapi |
| --- | --- | --- |
| Version history with rollback | Yes | Yes |
| Draft separate from live traffic | Yes | Yes |
| Production call grading | LLM judge on every finished call | Evals run mock conversations you author |

### Outbound and transfers

| | Assistable | Vapi |
| --- | --- | --- |
| Outbound campaigns | Yes | Yes |
| Campaign numbers | In-app numbers work | Requires imported provider number |
| Calling windows and retries | Timezone-aware windows, window-honoring retries | Overflow queued, retried a few minutes later |
| Warm transfer | Ordered fallbacks with answering-machine detection | Multiple modes, Twilio-based telephony only per docs |

### Pricing

| | Assistable | Vapi |
| --- | --- | --- |
| Voice | $0.07/min all-in | $0.05/min plus STT, LLM, and TTS at cost |
| Messages | $0.02 each | $0.005/msg plus model at cost |
| Concurrency | No per-line fees | 10 slots included; $10 per line/month on Build |
| Add-ons | None | HIPAA $2K/month, Zero Data Retention $1K/month |

## When Vapi is the right call

Vapi is the right call when you have engineers and want provider-level control. You can mix and match any STT, LLM, and TTS provider with your own API keys at zero markup, drive everything through a full API, SDK, and CLI surface including web calls, and use sophisticated transfer plans with AI-generated summaries and fallback behavior. Their published testing stack is the deepest in the category, with evals, simulations, voice and chat test suites, and scorecards, and they ship version history with diff preview and role-based access. If your team is building a bespoke voice product, wants its own backend running the business logic, and is willing to own webhooks, carrier setup, and Git-based config promotion across separate orgs, Vapi gives you more raw control than an operated platform will.

## FAQ

**What is the difference between Assistable and Vapi?**

Vapi gives developers an API to assemble a voice agent from the STT, LLM, and TTS providers they choose. Assistable is the operated alternative: telephony, versioning, campaigns, and QA ship built in at $0.07/min all-in.

**Is Assistable or Vapi 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. Vapi's published pricing model is $0.05/min + providers at cost. 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 Vapi over Assistable?**

Vapi is the right call when you have engineers and want provider-level control. You can mix and match any STT, LLM, and TTS provider with your own API keys at zero markup, drive everything through a full API, SDK, and CLI surface including web calls, and use sophisticated transfer plans with AI-generated summaries and fallback behavior. Their published testing stack is the deepest in the category, with evals, simulations, voice and chat test suites, and scorecards, and they ship version history with diff preview and role-based access. If your team is building a bespoke voice product, wants its own backend running the business logic, and is willing to own webhooks, carrier setup, and Git-based config promotion across separate orgs, Vapi gives you more raw control than an operated platform will.

**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/vapi