Retell AI alternative on your own SIP trunk: Wixzel Voice
Retell leans towards teams that want to design agents visually and deploy them at volume; Wixzel Voice is an HTTP API for developers who bring their own trunk.
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Written by Aqeel Shamsudheen, founder of Wixzel Voice, so read it as the interested party it is. Retell AI is described from its own public documentation at the level of business model, not rate, and every section names where it is the better choice.
Who is Retell AI for, and who is Wixzel Voice for?
Retell AI is for
teams that want a conversation-flow builder, provisioned numbers, batch campaigns and analytics in one product, with an API underneath.
Wixzel Voice is for
developers who want an API first, their own SIP trunk, and one prepaid balance covering every engine, and who accept an alpha product.
What is Retell AI?
Retell AI is a platform for building and deploying AI phone agents, with a conversation-flow builder, phone number provisioning, SIP support, batch calling and analytics.
How do Retell AI and Wixzel Voice compare, side by side?
| Attribute | Retell AI | Wixzel Voice |
|---|---|---|
| Telephony | Provisions numbers; also connects SIP trunks and existing carriers. | Bring your own SIP trunk for phone calls: no numbers or minutes sold, no markup on carrier rates. Agents also run in your web and mobile apps over a WebSocket, with no trunk. |
| Provider accounts | Platform-managed, with bring-your-own-key options for some models and voices. | Platform-owned. No Deepgram, ElevenLabs, OpenRouter, Sarvam or Google keys to bring. |
| Billing model | Per-minute pricing built from platform, model, voice and telephony components; enterprise tiers. | Prepaid credit spent per second, per token and per character, plus a flat orchestration fee; $0.0466 to $0.1851 per connected minute at typical speech rates. Every charge itemised. |
| Voice engines | A catalogue of models and voices chosen per agent. | 4 presets (classic, sarvam, gemini-live, deepgram-agent) or compose your own from named provider/model pairs. |
| SDKs | Official SDKs and a web SDK. | An official TypeScript SDK (npm: wixzel-voice) for TypeScript, JavaScript and edge runtimes, and an official Dart SDK (pub.dev: wixzel_voice) for Dart and Flutter, each with a realtime client for talking to an agent from a browser or app. Other languages use plain HTTP and JSON with an OpenAPI document. An official MCP server covers AI agents. |
| No-code builder | Yes, a visual conversation-flow builder plus prompt-based agents. | No. Agents are created with POST /v1/agents; the console is for keys, billing and logs. |
| Maturity | Established, venture-backed. | Alpha, deployed, operated by a sole proprietor in India. |
| Where it runs | United States. | Hetzner, Helsinki (EU), with providers in the US and India processing audio during a call; or your own servers, with a self-host license. |
Retell AI's rates are deliberately not quoted here: they change by tier and by month. Check its pricing page for current figures. Wixzel Voice's figures are generated from the price book.
Where is Retell AI better, and where is Wixzel Voice better?
Where Retell AI is better
- A visual flow builder, so an agent can be designed and tested by someone who does not write code.
- Analytics, call review tooling and post-call evaluation built in.
- Provisioned phone numbers, and a longer-established web calling SDK.
- Scale and a support organisation behind it.
Where Wixzel Voice is better
- One prepaid balance for every engine, itemised to the micro-dollar per usage row.
- Telephony at carrier cost over your own trunk.
- Indian languages end to end with the sarvam engine.
- Prices generated from the price book, so the published figure cannot be lower than the billed one.
Should you stay with Retell AI or try Wixzel Voice?
Stay with Retell AI if
- Non-developers on your team design the agents.
- You rely on Retell's analytics and evaluation tooling.
- You need provisioned numbers.
Try Wixzel Voice if
- You want an API and a trunk, not a builder.
- You want a single balance instead of per-component invoices.
- You are building for Indian languages.
Frequently asked questions
- Is Wixzel Voice a Retell AI alternative?
- For developers who bring their own SIP trunk and want an HTTP API with one prepaid balance, yes. For teams that design agents in a visual flow builder or depend on built-in analytics, Retell AI is the better fit.
- Does Wixzel Voice have a flow builder like Retell AI?
- No. Agents are defined by prompt and voice configuration through POST /v1/agents. The console covers keys, billing and logs, not agent design.
- Does Wixzel Voice do batch or campaign calling?
- Yes. Leads can be uploaded in bulk and a campaign started, paused and resumed through /v1/campaigns, with concurrency capped per account (5 by default).
How does Wixzel Voice compare with other voice agent APIs?
Both are APIs for building phone-calling AI agents. They differ on who owns the provider accounts, who sells the telephony, and how far along each product is.
Bland runs its own models and voices as a single integrated stack; Wixzel Voice composes engines from named third-party models and lets you see and pick each one.
This is the build-or-buy comparison rather than a like-for-like one. LiveKit Agents is a framework you write against and operate; Wixzel Voice is an HTTP API where the orchestration already runs. The real question is whether you want to own the agent runtime.
A build-or-buy comparison, like LiveKit Agents. Pipecat is a pipeline you assemble in Python and run yourself; Wixzel Voice is an HTTP API where the pipeline already runs. The question is whether the conversation loop is code you want to own.
Hosted platforms, a bring-your-own-trunk API and open-source frameworks, grouped by the team each one fits.
Something wrong about Retell AI? Corrections are welcome via the contact page.