Index: apps/app_voicemail.c
===================================================================
--- apps/app_voicemail.c	(revision 187763)
+++ apps/app_voicemail.c	(working copy)
@@ -40,10 +40,6 @@
  *        with a plan to clean this up.
  */
 
-/*** MODULEINFO
-	<depend>res_smdi</depend>
- ***/
-
 /*** MAKEOPTS
 <category name="MENUSELECT_OPTS_app_voicemail" displayname="Voicemail Build Options" positive_output="yes" remove_on_change="apps/app_voicemail.o apps/app_voicemail.so apps/app_directory.o apps/app_directory.so">
 	<member name="ODBC_STORAGE" displayname="Storage of Voicemail using ODBC">
@@ -10619,14 +10615,16 @@
 		if ((val = ast_variable_retrieve(cfg, "general", "smdienable")) && ast_true(val)) {
 			ast_debug(1, "Enabled SMDI voicemail notification\n");
 			if ((val = ast_variable_retrieve(cfg, "general", "smdiport"))) {
-				smdi_iface = ast_smdi_interface_find(val);
+				smdi_iface = ast_smdi_interface_find ? ast_smdi_interface_find(val) : NULL;
 			} else {
 				ast_debug(1, "No SMDI interface set, trying default (/dev/ttyS0)\n");
-				smdi_iface = ast_smdi_interface_find("/dev/ttyS0");
+				smdi_iface = ast_smdi_interface_find ? ast_smdi_interface_find("/dev/ttyS0") : NULL;
 			}
 			if (!smdi_iface) {
 				ast_log(AST_LOG_ERROR, "No valid SMDI interface specfied, disabling SMDI voicemail notification\n");
 			} 
+		} else {
+			smdi_iface = NULL;
 		}
 
 		/* Silence treshold */
Index: include/asterisk/smdi.h
===================================================================
--- include/asterisk/smdi.h	(revision 187763)
+++ include/asterisk/smdi.h	(working copy)
@@ -34,6 +34,7 @@
 #include <termios.h>
 #include <time.h>
 
+#include "asterisk/optional_api.h"
 #include "asterisk/config.h"
 #include "asterisk/module.h"
 #include "asterisk/astobj.h"
@@ -84,7 +85,8 @@
  */
 struct ast_smdi_interface;
 
-void ast_smdi_interface_unref(struct ast_smdi_interface *iface);
+AST_OPTIONAL_API(void, ast_smdi_interface_unref, (struct ast_smdi_interface *iface),
+		{ return; });
 
 /*! 
  * \brief Get the next SMDI message from the queue.
@@ -96,7 +98,8 @@
  *
  * \return the next SMDI message, or NULL if there were no pending messages.
  */
-struct ast_smdi_md_message *ast_smdi_md_message_pop(struct ast_smdi_interface *iface);
+AST_OPTIONAL_API(struct ast_smdi_md_message *, ast_smdi_md_message_pop,
+		(struct ast_smdi_interface *iface), { return NULL; });
 
 /*!
  * \brief Get the next SMDI message from the queue.
@@ -110,7 +113,8 @@
  * \return the next SMDI message, or NULL if there were no pending messages and
  * the timeout has expired.
  */
-struct ast_smdi_md_message *ast_smdi_md_message_wait(struct ast_smdi_interface *iface, int timeout);
+AST_OPTIONAL_API(struct ast_smdi_md_message *, ast_smdi_md_message_wait,
+		(struct ast_smdi_interface *iface, int timeout), { return NULL; });
 
 /*!
  * \brief Put an SMDI message back in the front of the queue.
@@ -121,7 +125,9 @@
  * should be used if a message was popped but is not going to be processed for
  * some reason, and the message needs to be returned to the queue.
  */
-void ast_smdi_md_message_putback(struct ast_smdi_interface *iface, struct ast_smdi_md_message *msg);
+AST_OPTIONAL_API(void, ast_smdi_md_message_putback,
+		(struct ast_smdi_interface *iface, struct ast_smdi_md_message *msg),
+		{ return; });
 
 /*!
  * \brief Get the next SMDI message from the queue.
@@ -133,7 +139,8 @@
  *
  * \return the next SMDI message, or NULL if there were no pending messages.
  */
-struct ast_smdi_mwi_message *ast_smdi_mwi_message_pop(struct ast_smdi_interface *iface);
+AST_OPTIONAL_API(struct ast_smdi_mwi_message *, ast_smdi_mwi_message_pop,
+		(struct ast_smdi_interface *iface), { return NULL; });
 
 /*!
  * \brief Get the next SMDI message from the queue.
@@ -147,9 +154,11 @@
  * \return the next SMDI message, or NULL if there were no pending messages and
  * the timeout has expired.
  */
-struct ast_smdi_mwi_message *ast_smdi_mwi_message_wait(struct ast_smdi_interface *iface, int timeout);
-struct ast_smdi_mwi_message *ast_smdi_mwi_message_wait_station(struct ast_smdi_interface *iface, 
-	int timeout, const char *station);
+AST_OPTIONAL_API(struct ast_smdi_mwi_message *, ast_smdi_mwi_message_wait,
+		(struct ast_smdi_interface *iface, int timeout), { return NULL; });
+AST_OPTIONAL_API(struct ast_smdi_mwi_message *, ast_smdi_mwi_message_wait_station,
+		(struct ast_smdi_interface *iface, int timeout, const char *station),
+		{ return NULL; });
 
 /*!
  * \brief Put an SMDI message back in the front of the queue.
@@ -160,7 +169,9 @@
  * should be used if a message was popped but is not going to be processed for
  * some reason, and the message needs to be returned to the queue.
  */
-void ast_smdi_mwi_message_putback(struct ast_smdi_interface *iface, struct ast_smdi_mwi_message *msg);
+AST_OPTIONAL_API(void, ast_smdi_mwi_message_putback,
+		(struct ast_smdi_interface *iface, struct ast_smdi_mwi_message *msg),
+		{ return; });
 
 /*!
  * \brief Find an SMDI interface with the specified name.
@@ -170,26 +181,32 @@
  * actually returns an ASTOBJ reference and should be released using
  * #ASTOBJ_UNREF(iface, ast_smdi_interface_destroy).
  */
-struct ast_smdi_interface *ast_smdi_interface_find(const char *iface_name);
+AST_OPTIONAL_API(struct ast_smdi_interface *, ast_smdi_interface_find,
+		(const char *iface_name), { return NULL; });
 
 /*!
  * \brief Set the MWI indicator for a mailbox.
  * \param iface the interface to use.
  * \param mailbox the mailbox to use.
  */
-int ast_smdi_mwi_set(struct ast_smdi_interface *iface, const char *mailbox);
+AST_OPTIONAL_API(int, ast_smdi_mwi_set,
+		(struct ast_smdi_interface *iface, const char *mailbox),
+		{ return -1; });
 
 /*! 
  * \brief Unset the MWI indicator for a mailbox.
  * \param iface the interface to use.
  * \param mailbox the mailbox to use.
  */
-int ast_smdi_mwi_unset(struct ast_smdi_interface *iface, const char *mailbox);
+AST_OPTIONAL_API(int, ast_smdi_mwi_unset,
+		(struct ast_smdi_interface *iface, const char *mailbox), { return -1; });
 
 /*! \brief ast_smdi_md_message destructor. */
-void ast_smdi_md_message_destroy(struct ast_smdi_md_message *msg);
+AST_OPTIONAL_API(void, ast_smdi_md_message_destroy,
+		(struct ast_smdi_md_message *msg), { return; });
 
 /*! \brief ast_smdi_mwi_message destructor. */
-void ast_smdi_mwi_message_destroy(struct ast_smdi_mwi_message *msg);
+AST_OPTIONAL_API(void, ast_smdi_mwi_message_destroy,
+		(struct ast_smdi_mwi_message *msg), { return; });
 
 #endif /* !ASTERISK_SMDI_H */
Index: res/res_smdi.c
===================================================================
--- res/res_smdi.c	(revision 187763)
+++ res/res_smdi.c	(working copy)
@@ -43,6 +43,7 @@
 #include "asterisk/module.h"
 #include "asterisk/lock.h"
 #include "asterisk/utils.h"
+#define AST_API_MODULE
 #include "asterisk/smdi.h"
 #include "asterisk/config.h"
 #include "asterisk/astobj.h"