Only decrease inringing count if above zero.

(issue #13238)
Reported by: kowalma

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@174710 65c4cc65-6c06-0410-ace0-fbb531ad65f3

diff --git a/channels/chan_sip.c b/channels/chan_sip.c
index d932dff..bfbdba3 100644 (file)
--- a/channels/chan_sip.c
+++ b/channels/chan_sip.c
@@ -5314,7 +5314,9 @@ static int update_call_counter(struct sip_pvt *fup, int event)
                        sip_pvt_lock(fup);
                        ao2_lock(p);
                        if (ast_test_flag(&fup->flags[0], SIP_INC_RINGING)) {
-                               (*inringing)--;
+                               if (*inringing > 0) {
+                                       (*inringing)--;
+                               }
                                ast_clear_flag(&fup->flags[0], SIP_INC_RINGING);
                        }
                        ao2_unlock(p);