From 346b766917f8b540ed182aa25fd4757f8059b40a Mon Sep 17 00:00:00 2001
From: Joshua Colp <jcolp@digium.com>
Date: Tue, 10 Feb 2009 20:16:57 +0000
Subject: [PATCH] Merged revisions 174710 via svnmerge from
 https://origsvn.digium.com/svn/asterisk/trunk

........
  r174710 | file | 2009-02-10 16:15:43 -0400 (Tue, 10 Feb 2009) | 4 lines

  Only decrease inringing count if above zero.
  (issue #13238)
  Reported by: kowalma
........


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.6.0@174711 65c4cc65-6c06-0410-ace0-fbb531ad65f3
---
 channels/chan_sip.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/channels/chan_sip.c b/channels/chan_sip.c
index 72d59360ce..39b4559f43 100644
--- a/channels/chan_sip.c
+++ b/channels/chan_sip.c
@@ -4643,7 +4643,9 @@ static int update_call_counter(struct sip_pvt *fup, int event)
 			sip_pvt_lock(fup);
 			ast_mutex_lock(pu_lock);
 			if (ast_test_flag(&fup->flags[0], SIP_INC_RINGING)) {
-				(*inringing)--;
+				if (*inringing > 0) {
+					(*inringing)--;
+				}
 				ast_clear_flag(&fup->flags[0], SIP_INC_RINGING);
 			}
 			ast_mutex_unlock(pu_lock);