===================================================================
--- channels/chan_sip.c (revision 318832)
+++ channels/chan_sip.c (working copy)
@@ -8306,6 +8306,7 @@
 
        /* SRTP */
        int secure_audio = FALSE;
+       int no_secure_audio = FALSE;
        int secure_video = FALSE;
 
        /* Others */
@@ -8425,10 +8426,13 @@
                                ast_log(LOG_WARNING, "unknown SDP media protocol in offer: %s\n", protocol);
                                continue;
                        }
+                       no_secure_audio = 1;
                        audio = TRUE;
                        p->offered_media[SDP_AUDIO].offered = TRUE;
                        numberofmediastreams++;
-                       portno = x;
+                        if (x) {
+                                  portno = x;
+                               }
 
                        /* Scan through the RTP payload types specified in a "m=" line: */
                        codecs = m + len;
@@ -8607,8 +8611,14 @@
        }
 
        if (secure_audio && !(p->srtp && (ast_test_flag(p->srtp, SRTP_CRYPTO_OFFER_OK)))) {
-               ast_log(LOG_WARNING, "Can't provide secure audio requested in SDP offer\n");
-               return -4;
+               if (no_secure_audio) {
+                       ast_log(LOG_WARNING, "Can't provide secure audio but peer offers also unsecure audio. Fall back to unsecure mode.\n");
+                       secure_audio=0;
+               } else {
+                       ast_log(LOG_WARNING, "Can't provide secure audio requested in SDP offer\n");
+                       return -4;
+               }
        }
 
        if (!secure_audio && p->srtp) {