fix: prevent duplicate SIP registration (module-level guard), extract real caller number from X-CALLERNO header

src/lib/sip-client.ts

@@ -223,10 +223,17 @@ export class SIPClient {
     }
 
     private extractCallerNumber(session: RTCSession): string {
-        // Try P-Asserted-Identity header first (most reliable for real caller ID)
         try {
             const request = session.direction === 'incoming' ? (session as any)._request : null;
             if (request) {
+                // Ozonetel sends the real caller number in X-CALLERNO header
+                const xCallerNo = request.getHeader('X-CALLERNO');
+                if (xCallerNo) {
+                    // Remove leading 0s or country code prefix (00919... → 919...)
+                    const cleaned = xCallerNo.replace(/^0+/, '');
+                    return cleaned;
+                }
+
                 // Check P-Asserted-Identity
                 const pai = request.getHeader('P-Asserted-Identity');
                 if (pai) {
@@ -241,11 +248,11 @@ export class SIPClient {
                     if (match) return match[1];
                 }
 
-                // Check X-Original-CallerID (custom header some PBX systems use)
+                // Check X-Original-CallerID
                 const xCid = request.getHeader('X-Original-CallerID');
                 if (xCid) return xCid;
 
-                // Check From header display name (sometimes contains the real number)
+                // Check From header display name
                 const fromDisplay = request.from?.display_name;
                 if (fromDisplay && /^\+?\d{7,}$/.test(fromDisplay)) {
                     return fromDisplay;