PJSIP Trunk & Gateway Bindings

The core SIP connectivity framework for Asterisk 2 operates on the modern PJSIP stack. This architecture handles inbound and outbound media negotiation across external carrier gateways, remote softphones, and Dinstar SIM arrays.

Trunk Handshake & Signaling Topology

The diagram below maps out how incoming SIP communications flow across internal authentication and transport validation layers:

graph TD
    %% Ingress Client
    subgraph ExternalNetwork["External Edge Nodes"]
        SipClient["SIP softphone / Gateway<br/>(Initiates INVITE Packet)"]
    end

    %% PJSIP Pipeline tier
    subgraph PjsipTier["Asterisk PJSIP Transport Module"]
        PjsipTrans["res_pjsip.so Engine<br/>(Socket Listeners)"]
        AuthLayer["PJSIP Authenticator<br/>(Validates MD5 Secrets)"]
    end

    %% Internal Database proxies
    subgraph LogicLedger["EF Core Live Registry"]
        EndpointRow[("ps_endpoints DB Table<br/>(Defines AOR & Codecs)")]
    end

    %% Dialplan Target
    subgraph EngineTarget["Routing Execution"]
        DialplanCore["Asterisk Core Dialplan<br/>(stasis Application Router)"]
    end

    %% Vectors
    SipClient ==>|"Raw UDP/TCP Handshake"| PjsipTrans
    PjsipTrans ==>|"Resolve Transport"| AuthLayer
    AuthLayer ==>|"Database Validation Hash"| EndpointRow
    EndpointRow ==>|"Authorize Credentials"| DialplanCore

    %% Fully Styled CSS Tokens
    classDef clientToken fill:#0f172a,stroke:#38bdf8,stroke-width:2px,color:#fff,rx:6px,ry:6px;
    classDef pjsipToken fill:#1e293b,stroke:#a855f7,stroke-width:2px,color:#fff,rx:6px,ry:6px;
    classDef dbToken fill:#312e81,stroke:#ec4899,stroke-width:2px,color:#fff,rx:6px,ry:6px;
    classDef targetToken fill:#065f46,stroke:#10b981,stroke-width:2px,color:#fff,rx:6px,ry:6px;

    class ExternalNetwork,SipClient clientToken;
    class PjsipTier,PjsipTrans,AuthLayer pjsipToken;
    class LogicLedger,EndpointRow dbToken;
    class EngineTarget,DialplanCore targetToken;

Technical PJSIP Modeling Guidelines

1. Endpoint Identity Isolation

Every device binding maps to distinct identifier rows inside configuration schemas. Shared endpoints are strictly forbidden to ensure session logging scripts record explicit audio legs accurately.

2. Zero-State NAT Traversal

Trunk configurations force connection symmetric formatting (rewrite_contact=yes) to route NAT media paths cleanly across restrictive hardware network setups.

# PJSIP Trunk & Gateway Bindings

The core SIP connectivity framework for **Asterisk 2** operates on the modern **PJSIP stack**. This architecture handles inbound and outbound media negotiation across external carrier gateways, remote softphones, and Dinstar SIM arrays.

---

## Trunk Handshake & Signaling Topology

The diagram below maps out how incoming SIP communications flow across internal authentication and transport validation layers:

```mermaid
graph TD
 %% Ingress Client
 subgraph ExternalNetwork["External Edge Nodes"]
 SipClient["SIP softphone / Gateway (Initiates INVITE Packet)"]
 end

%% PJSIP Pipeline tier
 subgraph PjsipTier["Asterisk PJSIP Transport Module"]
 PjsipTrans["res_pjsip.so Engine (Socket Listeners)"]
 AuthLayer["PJSIP Authenticator (Validates MD5 Secrets)"]
 end

%% Internal Database proxies
 subgraph LogicLedger["EF Core Live Registry"]
 EndpointRow[("ps_endpoints DB Table (Defines AOR & Codecs)")]
 end

%% Dialplan Target
 subgraph EngineTarget["Routing Execution"]
 DialplanCore["Asterisk Core Dialplan (stasis Application Router)"]
 end

%% Fully Styled CSS Tokens
    classDef clientToken fill:#0f172a,stroke:#38bdf8,stroke-width:2px,color:#fff,rx:6px,ry:6px;
    classDef pjsipToken fill:#1e293b,stroke:#a855f7,stroke-width:2px,color:#fff,rx:6px,ry:6px;
    classDef dbToken fill:#312e81,stroke:#ec4899,stroke-width:2px,color:#fff,rx:6px,ry:6px;
    classDef targetToken fill:#065f46,stroke:#10b981,stroke-width:2px,color:#fff,rx:6px,ry:6px;

class ExternalNetwork,SipClient clientToken;
    class PjsipTier,PjsipTrans,AuthLayer pjsipToken;
    class LogicLedger,EndpointRow dbToken;
    class EngineTarget,DialplanCore targetToken;
```

---

## Technical PJSIP Modeling Guidelines

### 1. Endpoint Identity Isolation
Every device binding maps to distinct identifier rows inside configuration schemas. Shared endpoints are strictly forbidden to ensure session logging scripts record explicit audio legs accurately.

### 2. Zero-State NAT Traversal
Trunk configurations force connection symmetric formatting (`rewrite_contact=yes`) to route NAT media paths cleanly across restrictive hardware network setups.