Vapi alternative on your own SIP trunk: Wixzel Voice vs Vapi
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.
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Written by Aqeel Shamsudheen, founder of Wixzel Voice, so read it as the interested party it is. Vapi 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 Vapi for, and who is Wixzel Voice for?
Vapi is for
teams that want a mature, feature-rich platform with SDKs, provisioned phone numbers, web calling and the option to bring their own provider keys.
Wixzel Voice is for
developers who already have or want their own SIP trunk, want one key and one prepaid balance to cover every engine, and are comfortable building on an alpha API.
What is Vapi?
Vapi is a developer platform for building voice AI agents, with SDKs, a web dashboard, phone number provisioning and a large catalogue of pluggable speech and model providers.
How do Vapi and Wixzel Voice compare, side by side?
| Attribute | Vapi | Wixzel Voice |
|---|---|---|
| Telephony | Provisions phone numbers and also accepts SIP trunks; web and browser calls too. | 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 | Use Vapi's provider access, or bring your own keys for many providers. | Platform-owned. No Deepgram, ElevenLabs, OpenRouter, Sarvam or Google keys to bring. |
| Billing model | A per-minute platform fee plus the underlying provider and telephony costs, paid to Vapi or to the providers directly when you bring keys. | 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 wide provider catalogue for transcription, models and voices, selectable per assistant. | 4 presets (classic, sarvam, gemini-live, deepgram-agent) or compose your own from named provider/model pairs. |
| SDKs | Official server and client SDKs in several languages, plus a web SDK for browser calls. | 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 dashboard for building and testing assistants and workflows. | No. Agents are created with POST /v1/agents; the console is for keys, billing and logs. |
| Maturity | Established, venture-backed, large community. | Alpha, deployed, operated by a sole proprietor in India. |
| Where it runs | United States, with a global customer base. | Hetzner, Helsinki (EU), with providers in the US and India processing audio during a call; or your own servers, with a self-host license. |
Vapi'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 Vapi better, and where is Wixzel Voice better?
Where Vapi is better
- Breadth. Vapi supports far more providers, voices and models, and adds features faster than a one-person alpha can.
- Web calling maturity. Both have browser SDKs, but Vapi's has been in production longer and its browser audio is higher fidelity; Wixzel Voice's web sessions carry phone-quality (8 kHz) audio today.
- Phone numbers. Vapi will sell you a number; Wixzel Voice requires you to bring a trunk first.
- A visual builder, testing tools and a community with answers already written.
Where Wixzel Voice is better
- One balance. Every engine is covered by a single prepaid credit with no provider keys or invoices to reconcile.
- Indian languages end to end with the sarvam engine, priced from the same book as everything else.
- Published, generated prices. Every per-minute figure on the site is produced from the price book the meter bills against.
- Telephony at carrier cost. Your trunk, your rates, no resale margin.
Should you stay with Vapi or try Wixzel Voice?
Stay with Vapi if
- You depend on a provider Wixzel Voice does not run.
- You need provisioned numbers or higher-fidelity browser audio.
- You need a vendor with a track record and a support team.
Try Wixzel Voice if
- You already run a SIP trunk and want to stop paying a telephony markup.
- You want one prepaid balance instead of a platform fee plus provider bills.
- You are building for Indian languages.
Frequently asked questions
- Is Wixzel Voice a Vapi alternative?
- For developers building phone agents over their own SIP trunk, or voice agents inside their own web and mobile apps, yes. For teams that need provisioned phone numbers or a mature platform, Vapi remains the safer choice today.
- Can I bring my own provider keys to Wixzel Voice like I can with Vapi?
- No. Wixzel Voice is deliberately not bring-your-own-key: the provider accounts are platform-owned and one prepaid balance covers all of them. Vapi supports both models.
- Which is cheaper, Wixzel Voice or Vapi?
- It depends on the engine, the telephony and whether you bring keys to Vapi. Wixzel Voice's engines are $0.0466 to $0.1851 per connected minute including the orchestration fee, with telephony at your carrier's rate. Vapi's published pricing is a per-minute platform fee plus provider and telephony costs; check its pricing page for current figures.
How does Wixzel Voice compare with other voice agent APIs?
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.
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 Vapi? Corrections are welcome via the contact page.