Dexter Adds a Phone Number — Dial In, Search APIs, Pay with Your Voice
Call +1 (561) 940-2402 and talk to Dexter. Search 765+ paid APIs, pay for calls with USDC, get results read back to you — no account needed. Link your phone number for wallet access and conversation memory.
An Agent That Picks Up the Phone
Dexter, the facilitator behind millions of x402 settlements, today launches Dexter Phone — a live voice line at +1 (561) 940-2402 where anyone can talk to Dexter, search the x402 marketplace, and pay for API calls in real time.
No account required. No app to download. Dial the number, ask for what you need, and Dexter handles the search, the payment, and the response while you're still on the line.
For users who link their phone number at dexter.cash/profile, Dexter recognizes them on the call, greets them by name, remembers previous conversations, and can access their managed wallet after SMS verification.
Anyone Can Call
The baseline experience requires nothing — just a phone. Call the number and Dexter can:
- Search the marketplace — "Find me a sentiment analysis API for SOL under ten cents"
- Pay for and call APIs — Dexter pays with USDC through the x402 facilitator and reads you the result
- Answer questions — About Dexter, x402, the marketplace, whatever
This works for anyone. No Dexter account. No wallet. No setup.
Registered Users Get More
Users who link their phone number unlock additional capabilities:
- Dexter knows who you are — Greeted by name, account context loaded automatically
- Wallet access — After reading back a 6-digit SMS code, Dexter can execute wallet operations on your behalf
- Conversation memory — Dexter remembers what you talked about last time and references it naturally
- Continuity — Your third call about the same topic picks up where you left off
Linking takes ten seconds at dexter.cash/profile. But it's optional.
Real-Time Voice, Not Transcribe-and-Respond
Dexter Phone isn't a voice-to-text wrapper around a chatbot. The system bridges Twilio's media streams directly to OpenAI's Realtime API over WebSocket — audio flows bidirectionally with no intermediate transcription step. Dexter hears, thinks, and speaks in the same stream.
The result is a conversation that feels natural:
- Semantic turn detection — Dexter knows when you're done talking vs. pausing to think
- Interruptible — Start talking and Dexter stops immediately
- Low latency — Responses begin in under a second
- Natural filler — "Let me check on that..." while tools execute, not dead silence
Under the Hood
| Layer | Stack |
|---|---|
| Voice | OpenAI Realtime API (gpt-realtime-1.5) + semantic VAD |
| Telephony | Twilio Programmable Voice + Media Streams (WebSocket) |
| Agent tools | Dexter Open MCP Gateway — x402_search, x402_pay |
| Caller lookup | STIR/SHAKEN attestation + Dexter API phone-to-account resolution |
| Wallet verification | Twilio Verify SMS OTP — required per session for any fund operation |
| Memory | Per-caller call log with topic summaries and tool usage history |
| Payments | x402 v2 settlement via Dexter Facilitator across Solana + 5 EVM chains |
Built with the @openai/agents SDK and TwilioRealtimeTransportLayer extension. Each inbound call spawns a dedicated RealtimeSession with dynamically injected caller context and tool set.
Security
Voice is inherently less controlled than an authenticated web session. The design accounts for that:
- No auth needed for search — Marketplace tools work for everyone, no verification required
- SMS OTP gates wallet ops — Dexter texts a 6-digit code before touching funds, every call
- Per-session only — Verification resets when the call ends
- STIR/SHAKEN logged — Caller attestation level recorded for every inbound call
- No secrets over voice — Private keys, seed phrases, and full balances are never spoken
Seven Surfaces, One Agent
| Surface | Interface | Best For |
|---|---|---|
| dexter.cash/chat | Text | Detailed analysis, long conversations |
| dexter.cash/voice | Browser voice | Hands-free at your desk |
| +1 (561) 940-2402 | Phone call | On the go, no screen |
| open.dexter.cash/mcp | MCP | Agent-to-agent, any framework |
| mcp.dexter.cash/mcp | Authenticated MCP | Managed wallet workflows |
| Telegram | Chat | Quick mobile questions |
| Alexa | Voice | Smart home, ambient |
Same Dexter. Same marketplace. Same facilitator.