Beyond Text: Building Seamless Voice AI Agents on LINE MINI App

A session at LINE THAILAND DEVELOPER CONFERENCE 2026

Transcript

1. Beyond Text Seamless Voice AI on LINE MINI App Dr. Winn Voravuthikunchai | CEO, BOTNOI Group
2. BOTNOI: from chat to voice On LINE since 2017 LINE BOT AWARDS 2017 · Conversation Engine Award Featured in The Matter 2017 2025 2026 BOTNOI Chatbot on LINE BOTNOI Voicebot Voicebot inside LINE One of Thailand’s first LINE chatbots AI that talks with customers by voice via LINE MINI App
3. What is a voicebot? An AI agent you talk to You speak You hear LLM ASR Automatic Speech Recognition Hears: speech → text TTS Large Language Model Thinks: understands, decides, acts Text-to-Speech Speaks: text → natural voice Tools & data CRM · booking · knowledge base Newer speech-to-speech models can do all three in a single model
4. Voicebots are good now Usable today, and getting better fast Talks like a person Replies fast Lets you interrupt Natural voice, rhythm and tone First words in about a second Stops and listens when you cut in Switches languages Handles noise Keeps improving Thai and English in one sentence Focuses on the speaker in busy places Better with every model release
5. Voicebot for public services
6. When do you switch? We switch modes, not stories. TYPE TALK
7. Type when… Talk when… The task decides the mode. Type when… Talk when… • Quiet places • Telling a story • Exact details • Follow-up questions • Something to review • Explaining a problem
8. LINE OA today Chat Call Messaging API → chatbot LINE Call → users call the OA Bot answers 24/7 Answered by people only Chatbot: yes. Voicebot: not yet.
9. LINE OA should have both One assistant. Two ways to talk. LINE OA Chatbot Voicebot Type: exact details, review Talk: stories, follow-ups Shared memory same customer · same context
10. The hard part is the switch In chat Taps Voicebot “The Internet is not working” “Talk” “Hi, how can I help you today?” Starts from zero Carry over every switch Who What Where we are Verified identity What they need Answered · still open
11. Where the voicebot lives LINE MINI App, opened from your OA Opens from your OA No install Mic + screen Same LINE user ID Rich menu, chat button or link A web app inside LINE Talk, then see and fix OA + MINI App, same provider Running today: our voice agent opens in LINE as a MINI App, linked from the OA rich menu
12. One customer behind both bots Chatbot Voicebot Messaging API webhook → user ID MINI App → ID token → verify One LINE user ID Read before replying Shared memory profile · summary · open tasks Write after talking
13. The handoff, step by step Customer 1 Chatbot · LINE OA 5 Voicebot · MINI App Taps “Talk” in chat 2 3 Shared memory Save summary + open tasks MINI App opens 4 Verify ID token, load context 6 Write summary + facts First words already use that context 7 Push summary into chat Step 7 is a push message: it counts toward your OA’s monthly message quota
14. What the shared memory holds Small. Structured. Confirmed. 1 Transcripts are long and include mishearings { "line_user_id": "U4af49…", "profile": { "name": "Ploy", "consent": true }, "summary": "Home internet slow since yesterday", "confirmed": { "router_light": "orange" }, "open_tasks": [ "Book a technician visit" ], "last_mode": "voice", "version": 7 } Facts, not just transcripts 2 Mark what was confirmed Customer-confirmed vs. AI-inferred 3 Send a short brief Load a summary at the start so first audio stays fast 4 Version every write Chat and voice can write at the same time
15. What to get right Before you connect chat and voice Identity Verify ID tokens on the server. One provider for OA + MINI App. Latency Load context before the first word. Never block the audio. Consent Use profile and recordings only with permission (PDPA). Security Verify webhook signatures. Shortlived voice credentials, keys on the server. Consistency Webhooks can repeat: dedupe by webhookEventId, version every write. Fallback & cost Mic or network fails → continue in chat. Watch voice minutes and push quota.
16. Live demo 1. Open it from LINE 2. Ask about BOTNOI 3. Interrupt mid-answer 4. Switch to English 5. Leave details → a lead Voice agent running as a LINE MINI App
17. Build it in 5 steps 1 One provider OA (Messaging API) + LINE MINI App channel 2 “Talk” in the rich menu Link it to the MINI App 3 Verify on the server liff.init() → ID token → LINE user ID 4 Mic on tap Short-lived session; keys stay on the server 5 Write back Save the summary, send it back to chat
18. Make it feel natural Tune these. Measure these. Tune Measure • First audio in about 1 second • Time to first audio • Don’t cut people off • “Had to repeat myself” rate • Stop when interrupted • Voice → chat completion • Thai–English, names, numbers • Interruptions handled • Mic denied → type instead
19. Chat & Voice Agents in LINE OA Give the best experience to your customers Try it for yourself