Index: chan_sip.c
===================================================================
--- chan_sip.c  (revision 280339)
+++ chan_sip.c  (working copy)
@@ -12514,8 +12514,19 @@
        }

        reqprep(&resp, p, sipmethod, seqno, newbranch);
-       if (sipmethod == SIP_CANCEL && p->answered_elsewhere) {
-               add_header(&resp, "Reason", "SIP;cause=200;text=\"Call completed elsewhere\"");
+       if (sipmethod == SIP_CANCEL) {
+               if (p->answered_elsewhere) {
+                       if (ast_test_flag(&p->flags[1], SIP_PAGE2_Q850_REASON))
+                               add_header(&resp, "Reason", "Q.850;cause=200;text=\"Call completed elsewhere\"");
+                       else
+                               add_header(&resp, "Reason", "SIP;cause=200;text=\"Call completed elsewhere\"");
+               }
+               else if (ast_test_flag(&p->flags[1], SIP_PAGE2_Q850_REASON) && p->hangupcause) {
+                       char buf[50];
+
+                       sprintf(buf, "Q.850;cause=%i", p->hangupcause & 0x7f);
+                       add_header(&resp, "Reason", buf);
+               }
        }

        return send_request(p, &resp, reliable, seqno ? seqno : p->ocseq);