Help CenterVoice AI AgentsBuild Your First Voice Agent

Build Your First Voice Agent

System prompts, persona, voice selection, latency-vs-quality trade-offs, and live test.

7 min readUpdated 2026-02-19

A Voxinity voice agent is a configured set of instructions, tools, and a voice — wrapped in a low-latency telephony pipeline. This guide walks through every meaningful setting.

1. Choose a template

Templates are starting prompts tuned for common roles: Inbound Receptionist, Outbound Lead Qualifier, Appointment Booker, Long-Term Care Intake, Real Estate Buyer Agent, etc. They are not magic — they're a head start.

2. The system prompt

Open the System Prompt tab. The prompt has three sections: Identity (who the agent is), Behavior (how it speaks and what it must/must not do), and Knowledge (business-specific facts). Keep each section under 150 words for best latency and steerability.

Don't over-instruct
Prompts over ~700 words start fighting themselves. If you have a lot of facts, move them into the Knowledge Base (RAG) instead of stuffing them into the prompt.

3. Voice & model

Voice presets
Flash (recommended)
$0.09/min — sub-300ms TTS, broad voice catalog. Use this 95% of the time.
Turbo
$0.09/min — slightly higher quality than Flash, same latency tier.
v3 / Multilingual
$0.12/min — premium voices, multi-language, ~100ms slower.

4. Greeting & first utterance

The first thing the caller hears is the greeting field, not the system prompt. Keep it under 12 words. Example: 'Hi, this is Sarah at Apex Marketing — how can I help you today?'

5. Tools (function calling)

Toggle on the built-in tools your agent should be able to fire: check_availability, book_appointment, update_contact, transfer_call, send_sms_followup, end_call, etc. Each tool you enable adds a definition to the agent's instructions — don't enable tools you don't actually want it to use.

6. Recording disclosure

Behavior tab → toggle Recording Disclosure on (recommended). When on, the agent reads a brief 'this call may be recorded' notice at the start of every call. Required by law in 12 US states and most of the EU — leave it on unless you have a legal reason not to.

7. Test the agent

  1. Click the 'Try It' iPhone mockup in the editor — runs the exact SMS pipeline (no voice, no calendars touched).
  2. Or assign a real number and dial it from your phone for a full voice test.
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