Index: channel.c
===================================================================
--- channel.c   (revision 37508)
+++ channel.c   (working copy)
@@ -3577,7 +3577,7 @@
                                        if (callee_warning)
                                                bridge_playfile(c1, c0, config->warning_sound, t);
                                }
-                               if (config->warning_freq) {
+                               if (config->warning_freq && time_left_ms > config->warning_freq + 5000) {
                                        nexteventts = ast_tvadd(nexteventts, ast_samp2tv(config->warning_freq, 1000));
                                } else
                                        nexteventts = ast_tvadd(config->start_time, ast_samp2tv(config->timelimit, 1000));