diff -urN asterisk-1.4.9.orig/channels/chan_iax2.c asterisk-1.4.9/channels/chan_iax2.c
--- asterisk-1.4.9.orig/channels/chan_iax2.c	2007-07-24 12:32:20.000000000 -0400
+++ asterisk-1.4.9/channels/chan_iax2.c	2007-08-01 15:43:47.000000000 -0400
@@ -715,6 +715,7 @@
 	time_t checktime;
 	ast_mutex_t lock;
 	ast_cond_t cond;
+	int ready_for_signal;
 	/*! if this thread is processing a full frame,
 	  some information about that frame will be stored
 	  here, so we can avoid dispatching any more full
@@ -900,6 +901,10 @@
 				} else {
 					/* All went well and the thread is up, so increment our count */
 					iaxdynamicthreadcount++;
+					
+					/* Wait for the thread to be ready before returning it to the caller */
+					while (!thread->ready_for_signal)
+						usleep(1);
 				}
 			}
 		}
@@ -7854,6 +7859,9 @@
 		/* Wait for something to signal us to be awake */
 		ast_mutex_lock(&thread->lock);
 
+		/* Flag that we're ready to accept signals */
+		thread->ready_for_signal = 1;
+		
 		/* Put into idle list if applicable */
 		if (put_into_idle)
 			insert_idle_thread(thread);