# Audio Codec Negotiation Arrays

To balance high-fidelity voice output against tight network latency allocations, **Asterisk 2** configures strict codec prioritization arrays. The communication engine negotiates supported audio strings automatically during SIP setup cycles.

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## Media Stream Prioritization Blueprint

The flow block below maps out the exact selection hierarchy determining final audio encoding payload settings:

```mermaid
graph TD
    %% Initial Offer
    subgraph IncomingSDP["Client SDP INVITE Offer"]
        OfferCodecs["Raw Payload Array<br/>(Includes: G722, PCMU, PCMA)"]
    end

    %% Internal Filter
    subgraph NegotiationEngine["PJSIP Translation Layer"]
        FilterDisallow["Disallow Stage<br/>(Drops unconfigured encodings: 'all')"]
        FilterAllow["Allow Array Ranker<br/>(Prioritizes: ulaw, alaw)"]
    end

    %% Target Channel
    subgraph FinalChannel["Active Audio Session"]
        PayloadG711["Standardized PCM Stream<br/>(64 kbps Delivery)"]
    end

    %% Links
    OfferCodecs ==>|"Pass SDP Payload"| FilterDisallow
    FilterDisallow ==>|"Apply Exclusions"| FilterAllow
    FilterAllow ==>|"Select Ranked Match"| PayloadG711

    %% Beautiful Aesthetic Design
    classDef sdpToken fill:#0f172a,stroke:#38bdf8,stroke-width:2px,color:#fff,rx:6px,ry:6px;
    classDef engineToken fill:#1e293b,stroke:#a855f7,stroke-width:2px,color:#fff,rx:6px,ry:6px;
    classDef channelToken fill:#065f46,stroke:#10b981,stroke-width:2px,color:#fff,rx:6px,ry:6px;

    class IncomingSDP,OfferCodecs sdpToken;
    class NegotiationEngine,FilterDisallow,FilterAllow engineToken;
    class FinalChannel,PayloadG711 channelToken;
```

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## Explicit Priority Directives

### 1. `PCMU` / `ulaw` Standard (G.711u)
The default preferred operational payload string configured across North American and enterprise carrier routes. Ensures zero compression distortion during interactive text-to-speech AI playback.

### 2. `PCMA` / `alaw` Fallback (G.711a)
Configured as the primary fallback choice to support clear outbound integrations targeting international telephony networks.