Mine

diff -u -r1.445 chan_zap.c
--- channels/chan_zap.c 16 May 2005 14:41:05 -0000      1.445
+++ channels/chan_zap.c 16 May 2005 17:08:17 -0000
@@ -960,6 +960,8 @@
        struct zt_pvt *p;
        int res = 0;
        int index;
+        struct ast_frame f = { AST_FRAME_CNG };
+
        p = ast->tech_pvt;
        ast_mutex_lock(&p->lock);
        index = zt_get_index(ast, p, 0);
@@ -988,8 +990,10 @@
                        zo.dialstr[2] = 0;
                        if ((res = ioctl(p->subs[SUB_REAL].zfd, ZT_DIAL, &zo)))
                                ast_log(LOG_WARNING, "Couldn't dial digit %c\n", digit);
-                       else
+                       else {
                                p->dialing = 1;
+                               res = ast_queue_frame(ast, &f);
+                       }
                }
        }
        ast_mutex_unlock(&p->lock);