diff --git a/zaptel/zaptel-base.c b/zaptel/zaptel-base.c
index e2931bf..5929e65 100644
--- zaptel/zaptel-base.c
+++ zaptel/zaptel-base.c
@@ -1906,6 +1908,13 @@ static ssize_t zt_chan_write(struct file *file, const char *usrbuf, size_t count
 		} else {
 			if (copy_from_user(chan->writebuf[res], usrbuf, amnt))
 				return -EFAULT;
+
+			if ((chan->flags & ZT_FLAG_HDLC) && chan->span->ioctl != NULL){
+				if (chan->span->ioctl(chan, ZT_DCHAN_TX_V2, amnt)==0){
+					return amnt;
+				}
+			}
+
 			chan->writen[res] = amnt;
 		}
 		chan->writeidx[res] = 0;
diff -dur zaptel.orig/zaptel.h zaptel/zaptel.h
--- zaptel.orig/zaptel.h	2005-10-03 10:52:43.094205960 -0400
+++ zaptel/zaptel.h	2005-10-03 10:48:53.974037520 -0400
@@ -611,6 +611,10 @@
  *  60-80 are reserved for private drivers
  *  80-85 are reserved for dynamic span stuff
  */
+#define ZT_DCHAN_TX 	_IOR (ZT_CODE, 60, int)
+#define ZT_DCHAN_TX_V1  ZT_DCHAN_TX
+#define ZT_DCHAN_TX_V2  ZT_DCHAN_TX
+
 
 /*
  * Create a dynamic span