A production-ready AI calling agent MVP needs working telephony (inbound/outbound), sub-second perceived latency or speech-to-speech, human transfer, call logs, CRM or webhook writes, basic evals, and documented retention - not just a convincing demo recording. Haris Ullah Khan uses this checklist on VoiceCake, Use Cortana, and trade vertical builds.
If you are about to hire for an AI calling agent, use this checklist in your RFP - or run it on what you already have. I use it on every voice engagement.
1. Telephony & session lifecycle
- Inbound DID mapped with failover
- Outbound caller ID verified (if applicable)
- Webhook auth on Twilio (or carrier) endpoints
- Graceful hang-up when caller drops mid-tool-call
- Voicemail / after-hours path defined
2. Conversation quality
- Target latency documented (cascade vs speech-to-speech)
- Barge-in / interruption handling tested
- Transfer phrase + warm transfer to human tested on real mobile networks
- Prompt version pinned per deployed agent
3. Intelligence & tools
- Tool schemas validated (no silent JSON failures)
- RAG/knowledge if product questions appear (Pinecone/mem0 guide)
- Fallback when LLM or STT provider errors
4. Data & CRM
- Every call writes call id, outcome, summary somewhere durable
- PII fields identified; retention period documented
- Post-call workflow (Temporal) if writes happen after hang-up
5. Observability & evals
- Dashboard: volume, avg duration, transfer rate, tool error rate
- 20+ labeled transcripts with pass/fail
- Alert on spike in zero-duration or instant hang-ups
6. Compliance (outbound)
- Consent / opt-out language
- Calling windows by timezone
- Retry caps
Vertical examples on this site
| Vertical | Case study |
|---|---|
| HVAC / trades | Lehigh HVAC |
| Home services | HVAC & roofing playbook |
| Real estate | GHL + Retell leads |
| Multi-tenant SaaS | Use Cortana voice |
| Open-source cascade template | LiveKit chained pipeline demo |
Hire: /hire-voice-ai-developer · Services: /services/voice-ai · Clone: VoiceAI-Backend · VoiceAI-Frontend
Common questions
What is the minimum feature set for a voice AI MVP?
Inbound answer, one scripted intent path, human transfer, transcript storage, and CRM/webhook logging. Add outbound only after inbound is stable.
How do you test voice agents before launch?
Golden-path calls, adversarial audio (noise, accents, interruptions), tool-failure injection, and human review of 20+ transcripts against a rubric.
Do I need Temporal for a calling agent?
Not for a single-flow MVP. Yes when post-call workflows, campaigns, or CRM sync must survive crashes and retries.
How fast can an MVP go live?
4–8 weeks with a senior voice AI developer and clear scope - longer for multi-tenant or multi-language.
Who builds production calling agents?
Haris Ullah Khan - HVAC Retell agents, Use Cortana telephony, VoiceCake multi-channel. Book at harisullahkhan.me/#contact.