Preview Tab
The Preview tab lets you talk to your agent directly from the browser, using your laptop's microphone and speakers. It's the fastest way to iterate on prompts and voices — no phone, no telephony provider, no charges.
How it works
You're talking to the agent over the same realtime stack that powers production phone calls. The only difference is the audio source:
- Production calls: audio comes in from a SIP trunk and goes back out through the trunk.
- Preview calls: audio comes from your browser microphone and goes back to your browser speakers.
Everything else — LLM, prompt, voice, STT, tools — runs identically. If it works in Preview, it'll work on a real call (modulo the audio codec quality of phone calls, which is lower).
Using the preview
- Open your agent's detail page.
- Click the Preview tab.
- Click Connect. Your browser will ask for microphone permission — approve it.
- The agent connects and (if greetings are enabled) speaks its first message.
- Talk normally. The agent listens, responds, and can call any tools you've enabled.
- Click Disconnect when you're done.
The preview is fully isolated per session — disconnecting clears the conversation history. Reconnecting starts a fresh call.
What works in Preview
- Full system prompt and goal
- Voice (you'll hear the same TTS voice you picked on the Voice tab)
- STT (your speech is transcribed by the same engine)
- Tool calling — built-in and workspace HTTP tools fire normally
- Knowledge base lookups
- Auto-scheduling intent detection
- Guardrails
What's different from a phone call
- No DTMF. You can't press digits because there's no keypad. If you need to test DTMF flows (e.g. IVR routing, "press 1 for support"), use Make Outbound Call to dial yourself.
- No voicemail detection. Voicemail-related logic only triggers on real PSTN calls.
- No SIP-specific behavior. Custom SIP headers, trunk-level routing, P-Asserted-Identity — none of these apply.
- Higher audio quality. Browser audio is wideband; phone audio is narrowband (8kHz). Voices sometimes sound noticeably better in Preview than on a real call. Always confirm on a real call before going live.
Troubleshooting
- Browser asks for mic permission and you said no: click the lock icon in your browser address bar, allow microphone, refresh the tab.
- You hear yourself echoing: wear headphones — laptop speakers can feed back into the mic.
- Agent doesn't respond: check the Logs tab for the call (Preview calls log just like real ones). The transcript usually reveals whether the issue was STT (it didn't hear you), LLM (it heard you but had nothing to say), or TTS (it replied silently).
- Agent's voice cuts in over yours: that's the interruption handler firing. Tuning interruption sensitivity is on the roadmap; for now, pause briefly between turns.
When to use Preview vs. a real call
| Use Preview when… | Use Make Outbound Call when… |
|---|---|
| Iterating on prompt and goal | Verifying audio quality on the phone codec |
| Testing tool calls and knowledge base | Testing DTMF or IVR routing |
| Checking voice and tone | Testing voicemail detection |
| Quick sanity check after every save | Final go-live verification |
For most of your iteration, Preview is the right tool — it's instant, free, and good enough for 90% of testing.