Architecture

OpenAI can be the realtime engine. GreetingHero owns the receptionist workflow.

The AI never gets direct database access. It can only request allowlisted tools controlled by GreetingHero.

Layer	V1 implementation	Reason
Telephony	Telnyx behind TelephonyProviderInterface	Carrier can be swapped without rebuilding call workflows.
Realtime AI	OpenAI behind RealtimeAIProviderInterface	AI provider can be swapped without changing tools or storage.
Tool engine	Allowlisted PHP tools	Model requests actions; GreetingHero authorizes and executes them.
Data	GreetingHero communication tables	Call records, transcripts, summaries, leads, and tool runs are owned by the product.