# Assistable vs Sierra

Sierra builds enterprise agents for large brands through an expert deployment team, priced per resolved outcome. Assistable is the self-serve alternative: sign up, get your first assistant and a local number, and make a live call in minutes at $0.07/min all-in.

- **Assistable:** Assistable runs the whole stack itself and hands you the controls. You sign up, the platform builds your first assistant during onboarding, you buy a local number in-app, and your first live call happens in minutes. Telephony, immutable versioning with one-click rollback, a campaign dial engine, and an LLM judge that grades every conversation are product features you operate directly, at published rates: $0.07/min all-in for voice, $0.02 per message, pay as you go.
- **Sierra:** Sierra is an enterprise Agent OS for large consumer brands, sold through a sales process and deployed with help from Sierra's own expert agent development team, typically in weeks. It overlays your existing contact center, sitting in front of or behind your IVR, and is priced per resolved outcome under a quote-based contract with no published rates.

## 01. Time to first live call

**Assistable:** Sign up at platform.assistable.ai and the platform builds your first assistant during onboarding, grants $10 in usage credit, and sells you a real US or Canadian local number in-app. Your first live call happens in minutes, in one sitting, with no sales call and no engineering. Full production rollouts run 2-3 days because there is no engagement team between you and the product.

- First assistant created automatically during onboarding
- Free local phone number plus $10 in calling credit at signup
- US or Canadian local number purchased in-app
- Full production rollouts in 2-3 days
- Free signup, pay as you go

**Sierra:** Sierra is sales-led, with no self-serve signup, no free trial, and no public pricing page. Their product page describes deployment in weeks, supported by an expert agent development team that has backed hundreds of deployments.

## 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 contact-center platform to integrate and no carrier account to bring. Web chat, SMS, and voice share one channel gateway, and identity resolution maps every phone number, email, and web visitor to one contact record before the agent runs. Compliance rails are built in: DNC scrubbing, honeypot detection, A2P 10DLC registration, and KYC review.

- US local and toll-free numbers searched and bought in-app by area code or city
- TLS SIP trunk provisioned automatically per imported number
- Durable outbox retries 5 times, backing off 30 seconds to 1 hour
- 0.4s median answer, 99.99% uptime SLA
- DNC scrubbing and A2P 10DLC registration built into the platform

**Sierra:** Sierra positions voice as a contact-center overlay: agents integrate with any call center platform and can sit in front of or behind traditional IVR systems. That model assumes you already operate the telephony estate, and escalations route back into your existing call center teams.

## 03. Version control and rollback

**Assistable:** Sierra earns real credit here, and Assistable gives you the same rigor as a self-serve product you can inspect. Edits autosave to a working draft while live traffic keeps executing the last published version, and publishing writes an immutable numbered version into an append-only commit log with the author recorded and a Live badge on whichever version the explicit deploy pointer serves. Rollback is one click. Branches stage bigger rewrites and merge into Main without changing the flow id, so phone numbers, endpoints, and channels never re-point.

- Live traffic never executes the open draft after first publish
- Append-only version history with author and Live badge in the UI
- One-click rollback moves the deploy pointer to any prior version
- Branch merges republish without changing the flow id
- Publish and rollback are role-gated and audit-logged

**Sierra:** Sierra publishes a genuine release-engineering story: each release is an immutable agent snapshot capturing model versions, knowledge bases, and prompts atomically, with instant rollback and A/B testing across releases. The public material describes snapshots, rollback, and A/B, and does not go deeper than that.

## 04. Call routing and transfers

**Assistable:** Transfers are a configurable engine inside the product, not an escalation into a separate contact-center platform. Warm transfer holds the caller on hold music, hunts your team in order with up to 6 dial attempts and a 25-second default ring timeout per attempt, screens every leg with answering-machine detection so voicemail never gets the call, and speaks a private briefing to the human, 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.

- Ordered fallback hunting: up to 6 dial attempts, 25-second default ring timeout
- Answering-machine detection screens each transfer leg
- LLM-generated whisper briefing from the live call transcript
- Tag rules route by contact tag per channel with priority and active hours
- A per-minute sweep force-resolves stale holds

**Sierra:** Sierra escalates to call center teams using AI-powered intent classification and skills-based routing, and every hand-off includes a detailed AI-generated summary with full context and history. The published model is escalation into your existing contact-center queues.

## 05. Outbound at scale

**Assistable:** Outbound is a campaign engine, not just an agent that can dial. The engine converges every minute, starting scheduled campaigns and topping running ones to their concurrency cap, with claim-first updates that make double-dials impossible. Calling windows are timezone-aware with day-of-week selection and overnight wrap, retries cover no-answer, busy, and failed while honoring the window, and a wallet at zero pauses the campaign with a stated reason instead of burning the list.

- A/B traffic splits must sum to 100 before a campaign starts
- Per-campaign concurrency and calls-per-minute caps
- Enroll up to 25,000 contacts by filter, hand-picked list, or CSV
- DND, blacklist, and E.164 checks gate every dial
- Outcomes reconcile seconds after hangup via the call webhook

**Sierra:** Sierra markets outbound voice with precise pickup detection, verified caller IDs, voicemail handling, and warm transfers, and calls it one of its fastest-growing features. The published story is proactive, agent-initiated calling rather than a campaign dialer.

## 06. Observability and QA

**Assistable:** Write monitor rules in plain English and an LLM judge grades every finished call and chat against them, not a daily sample. Verdicts cite the decisive moment in the transcript with a confidence score, and repeat failures cluster into issues. The AI then drafts a minimal prompt fix, shows a line diff, and proves it by replaying the failing conversation 3 times through the published flow; confidence is the measured pass rate, never self-reported.

- Every finished call and chat graded, not a sample
- Verdicts cite the decisive transcript moment with confidence
- Fixes replay the failing conversation 3 times; confidence is the measured pass rate
- Per-rule health: fire rate, drift, silence, human-overturn rate
- Auto-apply is off by default behind hard guardrails

**Sierra:** Experience Manager is strong and well-documented: real-time monitoring, resolution and CSAT metrics, and tag- and sentiment-based conversation sampling. The QA loop is human-centered, with SMEs formally annotating samples of conversations every day, and annotated conversations can become regression tests replayed against mock APIs.

## Side by side

### Getting started

| | Assistable | Sierra |
| --- | --- | --- |
| Self-serve signup | Yes | No |
| Time to first live call | Minutes, in one sitting | Weeks, with Sierra's deployment team |
| Try before you buy | $10 credit plus free local number at signup | No |

### Telephony and routing

| | Assistable | Sierra |
| --- | --- | --- |
| Runs its own telephony | Yes | Overlays your contact center |
| In-app number purchase | US local and toll-free, by area code or city | Not published |
| Warm transfer | Ordered hunting, AMD screening, whisper briefing | AI-generated summary on hand-off |
| Call recording and transcription | Yes | Yes |

### Versioning and QA

| | Assistable | Sierra |
| --- | --- | --- |
| Immutable versions with instant rollback | Yes | Yes |
| Visible commit log and branches | Append-only history, branches merge without changing the flow id | Not published |
| QA loop | LLM judge grades every conversation | Daily SME annotation on samples |
| Regression testing | Replay failing calls 3x, measured pass rate | Conversation tests against mock APIs |

### Pricing

| | Assistable | Sierra |
| --- | --- | --- |
| Model | Pay as you go | Outcome-based, quote only |
| Voice | $0.07/min all-in | No published rates |
| Messages | $0.02 per message | No published rates |
| Platform, seat, or setup fees | None | Not published |

## When Sierra is the right call

Sierra is a strong choice if you are a large consumer enterprise that wants a partner more than a tool. Outcome-based pricing means Sierra gets paid when a task completes, and escalated cases are in most cases free, which genuinely de-risks a big rollout. Their homepage lists SOC 2, ISO 27001, ISO 42001, HIPAA, GDPR, FedRAMP, and PCI DSS, they support PCI Level 1 card and ACH payments entirely over the phone, and voice runs in 55+ languages with mid-conversation switching. Their published quality lifecycle, with immutable release snapshots, daily SME annotation, and conversation regression tests against mock APIs, is the most mature in the category, and customers like Vanguard, SoFi, and Rocket Mortgage back it up. If you have an enterprise budget, complex integrations, and want an expert team accountable to resolution outcomes, request the demo.

## FAQ

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

Sierra builds enterprise agents for large brands through an expert deployment team, priced per resolved outcome. Assistable is the self-serve alternative: sign up, get your first assistant and a local number, and make a live call in minutes at $0.07/min all-in.

**Is Assistable or Sierra 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. Sierra's published pricing model is outcome-based, quote only. 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 Sierra over Assistable?**

Sierra is a strong choice if you are a large consumer enterprise that wants a partner more than a tool. Outcome-based pricing means Sierra gets paid when a task completes, and escalated cases are in most cases free, which genuinely de-risks a big rollout. Their homepage lists SOC 2, ISO 27001, ISO 42001, HIPAA, GDPR, FedRAMP, and PCI DSS, they support PCI Level 1 card and ACH payments entirely over the phone, and voice runs in 55+ languages with mid-conversation switching. Their published quality lifecycle, with immutable release snapshots, daily SME annotation, and conversation regression tests against mock APIs, is the most mature in the category, and customers like Vanguard, SoFi, and Rocket Mortgage back it up. If you have an enterprise budget, complex integrations, and want an expert team accountable to resolution outcomes, request the demo.

**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/sierra