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.

Media Stream Prioritization Blueprint

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

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;

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.