feat(fax): add fax routing, job tracking, inbox management, and T.38/UDPTL media support

rust/crates/proxy-engine/src/sip_leg.rs

@@ -108,6 +108,24 @@ impl SipLeg {
             ..Default::default()
         });
 
+        self.send_invite_with_sdp(from_uri, to_uri, sip_call_id, socket, sdp)
+            .await;
+    }
+
+    pub async fn send_invite_with_sdp(
+        &mut self,
+        from_uri: &str,
+        to_uri: &str,
+        sip_call_id: &str,
+        socket: &UdpSocket,
+        sdp: String,
+    ) {
+        let ip = self
+            .config
+            .public_ip
+            .as_deref()
+            .unwrap_or(&self.config.lan_ip);
+
         let invite = SipMessage::create_request(
             "INVITE",
             to_uri,
@@ -401,6 +419,10 @@ impl SipLeg {
             return SipLegAction::Send(ok.serialize());
         }
 
+        if method == "INVITE" || method == "UPDATE" {
+            return SipLegAction::InDialogRequest(method.to_string());
+        }
+
         SipLegAction::None
     }
 
@@ -436,6 +458,9 @@ pub enum SipLegAction {
     StateChange(LegState),
     /// Connected — send this ACK.
     ConnectedWithAck(Vec<u8>),
+    /// Provider sent an in-dialog request (re-INVITE / UPDATE) that needs
+    /// call-manager-specific handling.
+    InDialogRequest(String),
     /// Terminated with a reason.
     Terminated(String),
     /// Send 200 OK and terminate.