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Comparison · Vapi

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 published voice rates.

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The bottom line

Assistable

Assistable brings telephony, transfer logic, campaigns, version control and conversation review into one platform. Our team scopes the deployment around your workflows and systems, with pilot goals, rollout responsibilities and support agreed in your proposal. Published usage rates sit alongside the deployment plan.

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.

The real comparison

Six places the platforms actually differ.

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

01 / 06

Time to first live call

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

Assistable

Assistable provides the platform for building and operating your agents, with deployment scope agreed through a sales conversation. Together we map your workflow, integrations and handoffs, define a pilot and plan testing. The path to production reflects your technical and review requirements.

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.

Assistable delivers

Workflow and integration scope agreed upfront·Pilot goals and success criteria·Testing, rollout and support planned with your team

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, 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.

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.

Assistable delivers

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

03 / 06

Version control and rollback

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

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.

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.

Assistable delivers

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

04 / 06

Call routing and transfers

What happens when a caller needs a human.

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.

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.

Assistable delivers

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

05 / 06

Outbound at scale

Dialing a list without burning it.

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.

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.

Assistable delivers

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

06 / 06

Observability and QA

How you find out something went wrong.

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.

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.

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

At a glance

Side by side

Platform model

Voice stack
AssistableOperated end to end, one vendor
VapiYou choose STT, LLM, and TTS per assistant
Phone numbers
AssistableUS local and toll-free bought in-app
Vapi10 free US numbers; import your carrier for production
Dynamic call logic
AssistableFlow branches in the builder
VapiYour server via webhooks and controlUrl
Environments
AssistableBranches merge on one flow id
VapiSeparate orgs, Git configs, CI promotion

Versioning and QA

Version history with rollback
AssistableYes
VapiYes
Draft separate from live traffic
AssistableYes
VapiYes
Production call grading
AssistableLLM judge on every finished call
VapiEvals run mock conversations you author

Outbound and transfers

Outbound campaigns
AssistableYes
VapiYes
Campaign numbers
AssistableIn-app numbers work
VapiRequires imported provider number
Calling windows and retries
AssistableTimezone-aware windows, window-honoring retries
VapiOverflow queued, retried a few minutes later
Warm transfer
AssistableOrdered fallbacks with answering-machine detection
VapiMultiple modes, Twilio-based telephony only per docs

Pricing

Voice
Assistablepublished voice rates
Vapi$0.05/min plus STT, LLM, and TTS at cost
Messages
Assistable$0.02 each
Vapi$0.005/msg plus model at cost
Concurrency
AssistableNo per-line fees
Vapi10 slots included; $10 per line/month on Build
Add-ons
AssistablePII, knowledge base and observation charged when enabled
VapiHIPAA $2K/month, Zero Data Retention $1K/month

Vapi 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 Vapi, answered.

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 published voice rates.
Is Assistable or Vapi 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. Vapi's published pricing model is $0.05/min + providers at cost. The rate card explains the voice base and any additional charges for the providers and options you choose.
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?
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 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.

“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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