Index: channels/chan_sip.c
===================================================================
--- channels/chan_sip.c	(revision 69807)
+++ channels/chan_sip.c	(working copy)
@@ -8281,6 +8281,8 @@
 {
 	struct sip_pvt *p = data;
 
+	ast_mutex_lock(&p->lock);
+
 	switch(state) {
 	case AST_EXTENSION_DEACTIVATED:	/* Retry after a while */
 	case AST_EXTENSION_REMOVED:	/* Extension is gone */
@@ -8301,6 +8303,9 @@
 
 	if (option_verbose > 1)
 		ast_verbose(VERBOSE_PREFIX_1 "Extension Changed %s new state %s for Notify User %s\n", exten, ast_extension_state2str(state), p->username);
+	
+	ast_mutex_unlock(&p->lock);
+
 	return 0;
 }