> ## Documentation Index > Fetch the complete documentation index at: https://docs.slng.ai/llms.txt > Use this file to discover all available pages before exploring further. # The Execution Layer > The execution layer gives you control of your voice calls. It reduces latency and model cost across the pipeline, using your existing tools, while improving reliability. This layer is built to give you control of your voice calls. It reduces latency and model cost across the voice pipeline, using your existing tools, while improving reliability. ## The problem A 16-turn voice call makes 48 model calls: STT, LLM, and TTS on every turn. Without an execution layer, each of those 48 runs from scratch. At 1M calls per month, that is 48M inference calls, every one generated fresh regardless of whether the output has been produced before. The same consent disclosure. The same hold message. The same greeting. Generated from scratch, every time. ## What the execution layer changes Every turn is routed through the execution path it actually needs. Three stages, one for each part of the voice pipeline: | Stage | What it does | | ---------------------- | --------------------------------------------------------------------------------------------- | | **STT Routing** | Route input to the right transcription model, based on language, accent, noise, and cost. | | **Tiered Decisioning** | Determine whether the turn needs full LLM reasoning, local inference, or no inference at all. | | **Output Assembly** | Assemble TTS output from cache and synthesis. Don't generate what already exists. | These stages run across a global network of edge points, with regional execution that keeps data in-jurisdiction. ## The system improves under load Every call through the system improves routing decisions and cache coverage for the next one. Cost and latency decrease with usage. Reliability increases. * More calls, more cache coverage, fewer model calls, lower cost * More patterns observed, better routing decisions, lower latency * More providers configured, more failover options, higher reliability ## What customers see | Metric | Improvement | | --------------------------- | --------------------------- | | End-to-end latency per turn | Up to 48% reduction | | Total pipeline cost | Up to 57% reduction | | Call completion rate | Zero dropped, zero downtime | ## How to integrate SLNG works with the orchestrator and models you already use. The endpoints sit between your orchestrator and your providers. Architecture and the request lifecycle. How path selection works. Connect your orchestrator.