Index: channels/chan_zap.c
===================================================================
--- channels/chan_zap.c	(revision 74801)
+++ channels/chan_zap.c	(working copy)
@@ -1607,14 +1607,23 @@
 
 static inline int zt_set_hook(int fd, int hs)
 {
-	int x, res;
+	int x, res, count = 0;
+
 	x = hs;
 	res = ioctl(fd, ZT_HOOK, &x);
-	if (res < 0) 
-	{
+
+	while (res < 0 && count < 20) {
+		usleep(100000); /* 1/10 sec. */
+		x = hs;
+		res = ioctl(fd, ZT_HOOK, &x);
+		count++;
+	}
+
+	if (res < 0) {
 		if (errno == EINPROGRESS) return 0;
 		ast_log(LOG_WARNING, "zt hook failed: %s\n", strerror(errno));
 	}
+
 	return res;
 }