diff --git a/include/asterisk/res_pjsip.h b/include/asterisk/res_pjsip.h
index f38e0b39a62e8263775a1f2e8e70bedc08170d1c..b26aba90d0d335f08d7a3847caca1b5b5602ca7f 100644
--- a/include/asterisk/res_pjsip.h
+++ b/include/asterisk/res_pjsip.h
@@ -2980,6 +2980,11 @@ const char *ast_sip_get_host_ip_string(int af);
  */
 long ast_sip_threadpool_queue_size(void);
 
+/*!
+ * \brief Retrieve the SIP threadpool object
+ */
+struct ast_threadpool *ast_sip_threadpool(void);
+
 /*!
  * \brief Retrieve transport state
  * \since 13.7.1
diff --git a/res/res_pjsip.c b/res/res_pjsip.c
index c6594708bb22766ef8ede59f95cd291c11b319bc..0dcbcea83b3800ea38cb99455e7d125115b8fbe8 100644
--- a/res/res_pjsip.c
+++ b/res/res_pjsip.c
@@ -34,6 +34,7 @@
 #include "asterisk/utils.h"
 #include "asterisk/astobj2.h"
 #include "asterisk/module.h"
+#include "asterisk/serializer.h"
 #include "asterisk/threadpool.h"
 #include "asterisk/taskprocessor.h"
 #include "asterisk/uuid.h"
@@ -2840,7 +2841,7 @@
 #define SERIALIZER_POOL_SIZE		8
 
 /*! Pool of serializers to use if not supplied. */
-static struct ast_taskprocessor *serializer_pool[SERIALIZER_POOL_SIZE];
+static struct ast_serializer_pool *sip_serializer_pool;
 
 static pjsip_endpoint *ast_pjsip_endpoint;
 
@@ -4626,71 +4627,10 @@ struct ast_taskprocessor *ast_sip_create_serializer(const char *name)
 	return ast_sip_create_serializer_group(name, NULL);
 }
 
-/*!
- * \internal
- * \brief Shutdown the serializers in the default pool.
- * \since 14.0.0
- *
- * \return Nothing
- */
-static void serializer_pool_shutdown(void)
-{
-	int idx;
-
-	for (idx = 0; idx < SERIALIZER_POOL_SIZE; ++idx) {
-		ast_taskprocessor_unreference(serializer_pool[idx]);
-		serializer_pool[idx] = NULL;
-	}
-}
-
-/*!
- * \internal
- * \brief Setup the serializers in the default pool.
- * \since 14.0.0
- *
- * \retval 0 on success.
- * \retval -1 on error.
- */
-static int serializer_pool_setup(void)
-{
-	char tps_name[AST_TASKPROCESSOR_MAX_NAME + 1];
-	int idx;
-
-	for (idx = 0; idx < SERIALIZER_POOL_SIZE; ++idx) {
-		/* Create name with seq number appended. */
-		ast_taskprocessor_build_name(tps_name, sizeof(tps_name), "pjsip/default");
-
-		serializer_pool[idx] = ast_sip_create_serializer(tps_name);
-		if (!serializer_pool[idx]) {
-			serializer_pool_shutdown();
-			return -1;
-		}
-	}
-	return 0;
-}
-
-static struct ast_taskprocessor *serializer_pool_pick(void)
-{
-	int idx;
-	int pos = 0;
-
-	if (!serializer_pool[0]) {
-		return NULL;
-	}
-
-	for (idx = 1; idx < SERIALIZER_POOL_SIZE; ++idx) {
-		if (ast_taskprocessor_size(serializer_pool[idx]) < ast_taskprocessor_size(serializer_pool[pos])) {
-			pos = idx;
-		}
-	}
-
-	return serializer_pool[pos];
-}
-
 int ast_sip_push_task(struct ast_taskprocessor *serializer, int (*sip_task)(void *), void *task_data)
 {
 	if (!serializer) {
-		serializer = serializer_pool_pick();
+		serializer = ast_serializer_pool_get(sip_serializer_pool);
 	}
 
 	return ast_taskprocessor_push(serializer, sip_task, task_data);
@@ -4771,7 +4711,7 @@ int ast_sip_push_task_wait_serializer(struct ast_taskprocessor *serializer, int
 {
 	if (!serializer) {
 		/* Caller doesn't care which PJSIP serializer the task executes under. */
-		serializer = serializer_pool_pick();
+		serializer = ast_serializer_pool_get(sip_serializer_pool);
 		if (!serializer) {
 			/* No serializer picked to execute the task */
 			return -1;
@@ -5133,6 +5073,11 @@ long ast_sip_threadpool_queue_size(void)
 	return ast_threadpool_queue_size(sip_threadpool);
 }
 
+struct ast_threadpool *ast_sip_threadpool(void)
+{
+	return sip_threadpool;
+}
+
 #ifdef TEST_FRAMEWORK
 AST_TEST_DEFINE(xml_sanitization_end_null)
 {
@@ -5204,7 +5149,7 @@ static int unload_pjsip(void *data)
 	 * These calls need the pjsip endpoint and serializer to clean up.
 	 * If they're not set, then there's nothing to clean up anyway.
 	 */
-	if (ast_pjsip_endpoint && serializer_pool[0]) {
+	if (ast_pjsip_endpoint && sip_serializer_pool) {
 		ast_res_pjsip_cleanup_options_handling();
 		ast_res_pjsip_cleanup_message_filter();
 		ast_sip_destroy_distributor();
@@ -5340,7 +5285,9 @@ static int load_module(void)
 		goto error;
 	}
 
-	if (serializer_pool_setup()) {
+	sip_serializer_pool = ast_serializer_pool_create(
+		"pjsip/default", SERIALIZER_POOL_SIZE, sip_threadpool, -1);
+	if (!sip_serializer_pool) {
 		ast_log(LOG_ERROR, "Failed to create SIP serializer pool. Aborting load\n");
 		goto error;
 	}
@@ -5413,7 +5360,7 @@ error:
 
 	/* These functions all check for NULLs and are safe to call at any time */
 	ast_sip_destroy_scheduler();
-	serializer_pool_shutdown();
+	ast_serializer_pool_destroy(sip_serializer_pool);
 	ast_threadpool_shutdown(sip_threadpool);
 
 	return AST_MODULE_LOAD_DECLINE;
@@ -5444,7 +5391,7 @@ static int unload_module(void)
 	 */
 	ast_sip_push_task_wait_servant(NULL, unload_pjsip, NULL);
 	ast_sip_destroy_scheduler();
-	serializer_pool_shutdown();
+	ast_serializer_pool_destroy(sip_serializer_pool);
 	ast_threadpool_shutdown(sip_threadpool);
 
 	return 0;
diff --git a/res/res_pjsip_mwi.c b/res/res_pjsip_mwi.c
index c89d383855a07bf32b89b0407a9e927656675fb6..d7749fab6468ce3b6cea751212abb4b1e180ddcc 100644
--- a/res/res_pjsip_mwi.c
+++ b/res/res_pjsip_mwi.c
@@ -36,13 +36,15 @@
 #include "asterisk/logger.h"
 #include "asterisk/astobj2.h"
 #include "asterisk/taskprocessor.h"
+#include "asterisk/serializer.h"
 #include "asterisk/sorcery.h"
 #include "asterisk/stasis.h"
 #include "asterisk/mwi.h"
 
 struct mwi_subscription;
-static struct ao2_container *unsolicited_mwi;
-static struct ao2_container *solicited_mwi;
+
+AO2_GLOBAL_OBJ_STATIC(mwi_unsolicited);
+AO2_GLOBAL_OBJ_STATIC(mwi_solicited);
 
 static char *default_voicemail_extension;
 
@@ -57,8 +59,11 @@ static char *default_voicemail_extension;
 /*! Number of serializers in pool if one not supplied. */
 #define MWI_SERIALIZER_POOL_SIZE 8
 
+/*! Max timeout for all threads to join during an unload. */
+#define MAX_UNLOAD_TIMEOUT_TIME 10 /* Seconds */
+
 /*! Pool of serializers to use if not supplied. */
-static struct ast_taskprocessor *mwi_serializer_pool[MWI_SERIALIZER_POOL_SIZE];
+static struct ast_serializer_pool *mwi_serializer_pool;
 
 static void mwi_subscription_shutdown(struct ast_sip_subscription *sub);
 static void mwi_to_ami(struct ast_sip_subscription *sub, struct ast_str **buf);
@@ -129,117 +134,6 @@ struct mwi_subscription {
 	char id[1];
 };
 
-/*!
- * \internal
- * \brief Shutdown the serializers in the mwi pool.
- * \since 13.12.0
- *
- * \return Nothing
- */
-static void mwi_serializer_pool_shutdown(void)
-{
-	int idx;
-
-	for (idx = 0; idx < MWI_SERIALIZER_POOL_SIZE; ++idx) {
-		ast_taskprocessor_unreference(mwi_serializer_pool[idx]);
-		mwi_serializer_pool[idx] = NULL;
-	}
-}
-
-/*!
- * \internal
- * \brief Setup the serializers in the mwi pool.
- * \since 13.12.0
- *
- * \retval 0 on success.
- * \retval -1 on error.
- */
-static int mwi_serializer_pool_setup(void)
-{
-	char tps_name[AST_TASKPROCESSOR_MAX_NAME + 1];
-	int idx;
-
-	for (idx = 0; idx < MWI_SERIALIZER_POOL_SIZE; ++idx) {
-		/* Create name with seq number appended. */
-		ast_taskprocessor_build_name(tps_name, sizeof(tps_name), "pjsip/mwi");
-
-		mwi_serializer_pool[idx] = ast_sip_create_serializer(tps_name);
-		if (!mwi_serializer_pool[idx]) {
-			mwi_serializer_pool_shutdown();
-			return -1;
-		}
-	}
-	return 0;
-}
-
-/*!
- * \internal
- * \brief Pick a mwi serializer from the pool.
- * \since 13.12.0
- *
- * \retval least queue size task processor.
- */
-static struct ast_taskprocessor *get_mwi_serializer(void)
-{
-	int idx;
-	int pos;
-
-	if (!mwi_serializer_pool[0]) {
-		return NULL;
-	}
-
-	for (pos = idx = 0; idx < MWI_SERIALIZER_POOL_SIZE; ++idx) {
-		if (ast_taskprocessor_size(mwi_serializer_pool[idx]) < ast_taskprocessor_size(mwi_serializer_pool[pos])) {
-			pos = idx;
-		}
-	}
-
-	return mwi_serializer_pool[pos];
-}
-
-/*!
- * \internal
- * \brief Set taskprocessor alert levels for the serializers in the mwi pool.
- * \since 13.12.0
- *
- * \retval 0 on success.
- * \retval -1 on error.
- */
-static int mwi_serializer_set_alert_levels(void)
-{
-	int idx;
-	long tps_queue_high;
-	long tps_queue_low;
-
-	if (!mwi_serializer_pool[0]) {
-		return -1;
-	}
-
-	tps_queue_high = ast_sip_get_mwi_tps_queue_high();
-	if (tps_queue_high <= 0) {
-		ast_log(AST_LOG_WARNING, "Invalid taskprocessor high water alert trigger level '%ld'\n",
-			tps_queue_high);
-		tps_queue_high = AST_TASKPROCESSOR_HIGH_WATER_LEVEL;
-	}
-
-	tps_queue_low = ast_sip_get_mwi_tps_queue_low();
-	if (tps_queue_low < -1 || tps_queue_high < tps_queue_low) {
-		ast_log(AST_LOG_WARNING, "Invalid taskprocessor low water clear alert level '%ld'\n",
-			tps_queue_low);
-		tps_queue_low = -1;
-	}
-
-	for (idx = 0; idx < MWI_SERIALIZER_POOL_SIZE; ++idx) {
-		if (ast_taskprocessor_alert_set_levels(mwi_serializer_pool[idx], tps_queue_low, tps_queue_high)) {
-			ast_log(AST_LOG_WARNING, "Failed to set alert levels for MWI serializer pool #%d.\n",
-				idx);
-		}
-	}
-
-	return 0;
-}
-
-
 static void mwi_stasis_cb(void *userdata, struct stasis_subscription *sub,
 		struct stasis_message *msg);
 
@@ -688,13 +582,15 @@ static int unsubscribe_stasis(void *obj, void *arg, int flags)
 }
 
 static int create_unsolicited_mwi_subscriptions(struct ast_sip_endpoint *endpoint,
-		int recreate, int send_now);
+	int recreate, int send_now, struct ao2_container *unsolicited_mwi, struct ao2_container *solicited_mwi);
 
 static void mwi_subscription_shutdown(struct ast_sip_subscription *sub)
 {
 	struct mwi_subscription *mwi_sub;
 	struct ast_datastore *mwi_datastore;
 	struct ast_sip_endpoint *endpoint = NULL;
+	struct ao2_container *unsolicited_mwi;
+	struct ao2_container *solicited_mwi;
 
 	mwi_datastore = ast_sip_subscription_get_datastore(sub, MWI_DATASTORE);
 	if (!mwi_datastore) {
@@ -708,18 +604,25 @@ static void mwi_subscription_shutdown(struct ast_sip_subscription *sub)
 	endpoint = ast_sorcery_retrieve_by_id(ast_sip_get_sorcery(), "endpoint", mwi_sub->id);
 
 	ao2_ref(mwi_datastore, -1);
-	ao2_unlink(solicited_mwi, mwi_sub);
+
+	solicited_mwi = ao2_global_obj_ref(mwi_solicited);
+	if (solicited_mwi) {
+		ao2_unlink(solicited_mwi, mwi_sub);
+	}
 
 	/*
 	 * When a solicited subscription is removed it's possible an unsolicited one
 	 * needs to be [re-]created. Attempt to establish unsolicited MWI.
 	 */
+	unsolicited_mwi = ao2_global_obj_ref(mwi_unsolicited);
 	if (unsolicited_mwi && endpoint) {
 		ao2_lock(unsolicited_mwi);
-		create_unsolicited_mwi_subscriptions(endpoint, 1, 1);
+		create_unsolicited_mwi_subscriptions(endpoint, 1, 1, unsolicited_mwi, solicited_mwi);
 		ao2_unlock(unsolicited_mwi);
+		ao2_ref(unsolicited_mwi, -1);
 	}
 
+	ao2_cleanup(solicited_mwi);
 	ao2_cleanup(endpoint);
 }
 
@@ -785,6 +688,10 @@ static int has_mwi_subscription(struct ao2_container *container,
 	*mwi_sub = NULL;
 	*mwi_stasis = NULL;
 
+	if (!container) {
+		return 0;
+	}
+
 	mwi_subs = ao2_find(container, ast_sorcery_object_get_id(endpoint),
 						OBJ_SEARCH_KEY | OBJ_MULTIPLE | OBJ_NOLOCK);
 	if (!mwi_subs) {
@@ -814,11 +721,13 @@ static int has_mwi_subscription(struct ao2_container *container,
  *
  * \param endpoint The endpoint
  * \param mailbox The mailbox
+ * \param unsolicited_mwi A container of unsolicited mwi objects
  *
  * \retval 1 if a solicited subscription is allowed for the endpoint/mailbox
  *         0 otherwise
  */
-static int allow_and_or_replace_unsolicited(struct ast_sip_endpoint *endpoint, const char *mailbox)
+static int allow_and_or_replace_unsolicited(struct ast_sip_endpoint *endpoint, const char *mailbox,
+	struct ao2_container *unsolicited_mwi)
 {
 	struct mwi_subscription *mwi_sub;
 	struct mwi_stasis_subscription *mwi_stasis;
@@ -865,11 +774,14 @@ static int send_notify(void *obj, void *arg, int flags);
  *
  * \param endpoint The endpoint
  * \param mailbox The mailbox
+ * \param unsolicited_mwi A container of unsolicited mwi objects
+ * \param solicited_mwi A container of solicited mwi objects
  *
  * \retval 1 if an unsolicited subscription is allowed for the endpoint/mailbox
  *         0 otherwise
  */
-static int is_unsolicited_allowed(struct ast_sip_endpoint *endpoint, const char *mailbox)
+static int is_unsolicited_allowed(struct ast_sip_endpoint *endpoint, const char *mailbox,
+	struct ao2_container *unsolicited_mwi, struct ao2_container *solicited_mwi)
 {
 	struct mwi_subscription *mwi_sub;
 	struct mwi_stasis_subscription *mwi_stasis;
@@ -935,28 +847,41 @@ static int mwi_validate_for_aor(void *obj, void *arg, int flags)
 	struct ast_sip_endpoint *endpoint = arg;
 	char *mailboxes;
 	char *mailbox;
+	struct ao2_container *unsolicited_mwi;
 
 	if (ast_strlen_zero(aor->mailboxes)) {
 		return 0;
 	}
 
 	/* A reload could be taking place so lock while checking if allowed */
-	ao2_lock(unsolicited_mwi);
+	unsolicited_mwi = ao2_global_obj_ref(mwi_unsolicited);
+	if (unsolicited_mwi) {
+		ao2_lock(unsolicited_mwi);
+	}
+
 	mailboxes = ast_strdupa(aor->mailboxes);
 	while ((mailbox = ast_strip(strsep(&mailboxes, ",")))) {
 		if (ast_strlen_zero(mailbox)) {
 			continue;
 		}
 
-		if (!allow_and_or_replace_unsolicited(endpoint, mailbox)) {
+		if (!allow_and_or_replace_unsolicited(endpoint, mailbox, unsolicited_mwi)) {
 			ast_debug(1, "Endpoint '%s' already configured for unsolicited MWI for mailbox '%s'. "
 					"Denying MWI subscription to %s\n", ast_sorcery_object_get_id(endpoint), mailbox,
 					ast_sorcery_object_get_id(aor));
-			ao2_unlock(unsolicited_mwi);
+
+			if (unsolicited_mwi) {
+				ao2_unlock(unsolicited_mwi);
+				ao2_ref(unsolicited_mwi, -1);
+			}
 			return -1;
 		}
 	}
-	ao2_unlock(unsolicited_mwi);
+
+	if (unsolicited_mwi) {
+		ao2_unlock(unsolicited_mwi);
+		ao2_ref(unsolicited_mwi, -1);
+	}
 
 	return 0;
 }
@@ -1082,6 +1007,7 @@ static int mwi_subscription_established(struct ast_sip_subscription *sip_sub)
 	const char *resource = ast_sip_subscription_get_resource_name(sip_sub);
 	struct mwi_subscription *sub;
 	struct ast_sip_endpoint *endpoint = ast_sip_subscription_get_endpoint(sip_sub);
+	struct ao2_container *solicited_mwi;
 
 	/* no aor in uri? subscribe to all on endpoint */
 	if (ast_strlen_zero(resource)) {
@@ -1102,7 +1028,12 @@ static int mwi_subscription_established(struct ast_sip_subscription *sip_sub)
 		ast_sip_subscription_remove_datastore(sip_sub, MWI_DATASTORE);
 	}
 
-	ao2_link(solicited_mwi, sub);
+	solicited_mwi = ao2_global_obj_ref(mwi_solicited);
+	if (solicited_mwi) {
+		ao2_link(solicited_mwi, sub);
+		ao2_ref(solicited_mwi, -1);
+	}
+
 	ao2_cleanup(sub);
 	ao2_cleanup(endpoint);
 	return 0;
@@ -1213,7 +1144,7 @@ static int send_notify(void *obj, void *arg, int flags)
 	struct mwi_subscription *mwi_sub = obj;
 	struct ast_taskprocessor *serializer = mwi_sub->is_solicited
 		? ast_sip_subscription_get_serializer(mwi_sub->sip_sub)
-		: get_mwi_serializer();
+		: ast_serializer_pool_get(mwi_serializer_pool);
 
 	if (ast_sip_push_task(serializer, serialized_notify, ao2_bump(mwi_sub))) {
 		ao2_ref(mwi_sub, -1);
@@ -1228,7 +1159,8 @@ static void mwi_stasis_cb(void *userdata, struct stasis_subscription *sub,
 	struct mwi_subscription *mwi_sub = userdata;
 
 	if (stasis_subscription_final_message(sub, msg)) {
-		if (ast_sip_push_task(NULL, serialized_cleanup, ao2_bump(mwi_sub))) {
+		if (ast_sip_push_task(ast_serializer_pool_get(mwi_serializer_pool),
+				serialized_cleanup, ao2_bump(mwi_sub))) {
 			ao2_ref(mwi_sub, -1);
 		}
 		return;
@@ -1248,11 +1180,13 @@ static void mwi_stasis_cb(void *userdata, struct stasis_subscription *sub,
  * \param endpoint An endpoint object
  * \param recreate Whether or not unsolicited subscriptions are potentially being recreated
  * \param send_now Whether or not to send a notify once the subscription is created
+ * \param unsolicited_mwi A container of unsolicited mwi objects
+ * \param solicited_mwi A container of solicited mwi objects
  *
  * \retval 0
  */
 static int create_unsolicited_mwi_subscriptions(struct ast_sip_endpoint *endpoint,
-		int recreate, int send_now)
+	int recreate, int send_now, struct ao2_container *unsolicited_mwi, struct ao2_container *solicited_mwi)
 {
 	RAII_VAR(struct mwi_subscription *, aggregate_sub, NULL, ao2_cleanup);
 	char *mailboxes;
@@ -1287,14 +1221,16 @@ static int create_unsolicited_mwi_subscriptions(struct ast_sip_endpoint *endpoin
 	}
 
 	/* Lock solicited so we don't potentially add to both containers */
-	ao2_lock(solicited_mwi);
+	if (solicited_mwi) {
+		ao2_lock(solicited_mwi);
+	}
 
 	mailboxes = ast_strdupa(endpoint->subscription.mwi.mailboxes);
 	while ((mailbox = ast_strip(strsep(&mailboxes, ",")))) {
 		struct mwi_subscription *sub;
 		struct mwi_stasis_subscription *mwi_stasis_sub;
 
-		if (!is_unsolicited_allowed(endpoint, mailbox)) {
+		if (!is_unsolicited_allowed(endpoint, mailbox, unsolicited_mwi, solicited_mwi)) {
 			continue;
 		}
 
@@ -1334,13 +1270,16 @@ static int create_unsolicited_mwi_subscriptions(struct ast_sip_endpoint *endpoin
 		}
 	}
 
-	ao2_unlock(solicited_mwi);
+	if (solicited_mwi) {
+		ao2_unlock(solicited_mwi);
+	}
+
 	return 0;
 }
 
-static int create_mwi_subscriptions_for_endpoint(void *obj, void *arg, int flags)
+static int create_mwi_subscriptions_for_endpoint(void *obj, void *arg, void *data, int flags)
 {
-	return create_unsolicited_mwi_subscriptions(obj, 0, 0);
+	return create_unsolicited_mwi_subscriptions(obj, 0, 0, arg, data);
 }
 
 static int unsubscribe(void *obj, void *arg, int flags)
@@ -1354,9 +1293,16 @@ static int unsubscribe(void *obj, void *arg, int flags)
 
 static void create_mwi_subscriptions(void)
 {
+	struct ao2_container *unsolicited_mwi;
+	struct ao2_container *solicited_mwi;
 	struct ao2_container *endpoints;
 	struct ast_variable *var;
 
+	unsolicited_mwi = ao2_global_obj_ref(mwi_unsolicited);
+	if (!unsolicited_mwi) {
+		return;
+	}
+
 	var = ast_variable_new("mailboxes !=", "", "");
 
 	endpoints = ast_sorcery_retrieve_by_fields(ast_sip_get_sorcery(), "endpoint",
@@ -1364,9 +1310,12 @@ static void create_mwi_subscriptions(void)
 
 	ast_variables_destroy(var);
 	if (!endpoints) {
+		ao2_ref(unsolicited_mwi, -1);
 		return;
 	}
 
+	solicited_mwi = ao2_global_obj_ref(mwi_solicited);
+
 	/* We remove all the old stasis subscriptions first before applying the new configuration. This
 	 * prevents a situation where there might be multiple overlapping stasis subscriptions for an
 	 * endpoint for mailboxes. Though there may be mailbox changes during the gap between unsubscribing
@@ -1375,10 +1324,12 @@ static void create_mwi_subscriptions(void)
 	 */
 	ao2_lock(unsolicited_mwi);
 	ao2_callback(unsolicited_mwi, OBJ_NOLOCK | OBJ_UNLINK | OBJ_NODATA | OBJ_MULTIPLE, unsubscribe, NULL);
-	ao2_callback(endpoints, OBJ_NODATA, create_mwi_subscriptions_for_endpoint, NULL);
+	ao2_callback_data(endpoints, OBJ_NODATA, create_mwi_subscriptions_for_endpoint, unsolicited_mwi, solicited_mwi);
 	ao2_unlock(unsolicited_mwi);
 
 	ao2_ref(endpoints, -1);
+	ao2_cleanup(solicited_mwi);
+	ao2_ref(unsolicited_mwi, -1);
 }
 
 /*! \brief Function called to send MWI NOTIFY on any unsolicited mailboxes relating to this AOR */
@@ -1391,7 +1342,8 @@ static int send_contact_notify(void *obj, void *arg, int flags)
 		return 0;
 	}
 
-	if (ast_sip_push_task(get_mwi_serializer(), serialized_notify, ao2_bump(mwi_sub))) {
+	if (ast_sip_push_task(ast_serializer_pool_get(mwi_serializer_pool),
+			serialized_notify, ao2_bump(mwi_sub))) {
 		ao2_ref(mwi_sub, -1);
 	}
 
@@ -1404,6 +1356,8 @@ static void mwi_contact_changed(const struct ast_sip_contact *contact)
 	char *id = ast_strdupa(ast_sorcery_object_get_id(contact));
 	char *aor = NULL;
 	struct ast_sip_endpoint *endpoint = NULL;
+	struct ao2_container *unsolicited_mwi;
+	struct ao2_container *solicited_mwi;
 
 	if (contact->endpoint) {
 		endpoint = ao2_bump(contact->endpoint);
@@ -1418,10 +1372,20 @@ static void mwi_contact_changed(const struct ast_sip_contact *contact)
 		return;
 	}
 
+	unsolicited_mwi = ao2_global_obj_ref(mwi_unsolicited);
+	if (!unsolicited_mwi) {
+		ao2_cleanup(endpoint);
+		return;
+	}
+
+	solicited_mwi = ao2_global_obj_ref(mwi_solicited);
+
 	ao2_lock(unsolicited_mwi);
-	create_mwi_subscriptions_for_endpoint(endpoint, NULL, 0);
+	create_unsolicited_mwi_subscriptions(endpoint, 0, 0, unsolicited_mwi, solicited_mwi);
 	ao2_unlock(unsolicited_mwi);
 	ao2_cleanup(endpoint);
+	ao2_cleanup(solicited_mwi);
+	ao2_ref(unsolicited_mwi, -1);
 
 	aor = strsep(&id, ";@");
 	ao2_callback(unsolicited_mwi, OBJ_NODATA, send_contact_notify, aor);
@@ -1447,6 +1411,7 @@ static void mwi_contact_deleted(const void *object)
 	struct mwi_subscription *mwi_sub;
 	struct ast_sip_endpoint *endpoint = NULL;
 	struct ast_sip_contact *found_contact;
+	struct ao2_container *unsolicited_mwi;
 
 	if (contact->endpoint) {
 		endpoint = ao2_bump(contact->endpoint);
@@ -1469,6 +1434,11 @@ static void mwi_contact_deleted(const void *object)
 		return;
 	}
 
+	unsolicited_mwi = ao2_global_obj_ref(mwi_unsolicited);
+	if (!unsolicited_mwi) {
+		return;
+	}
+
 	ao2_lock(unsolicited_mwi);
 	mwi_subs = ao2_find(unsolicited_mwi, contact->endpoint_name,
 		OBJ_SEARCH_KEY | OBJ_MULTIPLE | OBJ_NOLOCK | OBJ_UNLINK);
@@ -1479,6 +1449,7 @@ static void mwi_contact_deleted(const void *object)
 		ao2_iterator_destroy(mwi_subs);
 	}
 	ao2_unlock(unsolicited_mwi);
+	ao2_ref(unsolicited_mwi, -1);
 }
 
 /*! \brief Observer for contacts so unsolicited MWI is sent when a contact changes */
@@ -1491,7 +1462,12 @@ static const struct ast_sorcery_observer mwi_contact_observer = {
 /*! \brief Task invoked to send initial MWI NOTIFY for unsolicited */
 static int send_initial_notify_all(void *obj)
 {
-	ao2_callback(unsolicited_mwi, OBJ_NODATA, send_notify, NULL);
+	struct ao2_container *unsolicited_mwi = ao2_global_obj_ref(mwi_unsolicited);
+
+	if (unsolicited_mwi) {
+		ao2_callback(unsolicited_mwi, OBJ_NODATA, send_notify, NULL);
+		ao2_ref(unsolicited_mwi, -1);
+	}
 
 	return 0;
 }
@@ -1513,7 +1489,8 @@ static void mwi_startup_event_cb(void *data, struct stasis_subscription *sub, st
 		return;
 	}
 
-	ast_sip_push_task(NULL, send_initial_notify_all, NULL);
+	ast_sip_push_task(ast_serializer_pool_get(mwi_serializer_pool),
+		send_initial_notify_all, NULL);
 
 	stasis_unsubscribe(sub);
 }
@@ -1522,7 +1499,8 @@ static void global_loaded(const char *object_type)
 {
 	ast_free(default_voicemail_extension);
 	default_voicemail_extension = ast_sip_get_default_voicemail_extension();
-	mwi_serializer_set_alert_levels();
+	ast_serializer_pool_set_alerts(mwi_serializer_pool,
+		ast_sip_get_mwi_tps_queue_high(), ast_sip_get_mwi_tps_queue_low());
 }
 
 static struct ast_sorcery_observer global_observer = {
@@ -1537,32 +1515,65 @@ static int reload(void)
 	return 0;
 }
 
+static int unload_module(void)
+{
+	struct ao2_container *unsolicited_mwi;
+
+	ast_sorcery_observer_remove(ast_sip_get_sorcery(), "global", &global_observer);
+	ast_sorcery_observer_remove(ast_sip_get_sorcery(), "contact", &mwi_contact_observer);
+
+	unsolicited_mwi = ao2_global_obj_replace(mwi_unsolicited, NULL);
+	if (unsolicited_mwi) {
+		ao2_callback(unsolicited_mwi, OBJ_UNLINK | OBJ_NODATA | OBJ_MULTIPLE, unsubscribe, NULL);
+		ao2_ref(unsolicited_mwi, -1);
+	}
+
+	ao2_global_obj_release(mwi_solicited);
+
+	if (ast_serializer_pool_destroy(mwi_serializer_pool)) {
+		ast_log(LOG_WARNING, "Unload incomplete. Try again later\n");
+		return -1;
+	}
+	mwi_serializer_pool = NULL;
+
+	ast_sip_unregister_subscription_handler(&mwi_handler);
+
+	ast_free(default_voicemail_extension);
+	default_voicemail_extension = NULL;
+	return 0;
+}
+
 static int load_module(void)
 {
+	struct ao2_container *mwi_container;
+
 	if (ast_sip_register_subscription_handler(&mwi_handler)) {
 		return AST_MODULE_LOAD_DECLINE;
 	}
 
-	if (mwi_serializer_pool_setup()) {
+	mwi_serializer_pool = ast_serializer_pool_create("pjsip/mwi",
+		MWI_SERIALIZER_POOL_SIZE, ast_sip_threadpool(), MAX_UNLOAD_TIMEOUT_TIME);
+	if (!mwi_serializer_pool) {
 		ast_log(AST_LOG_WARNING, "Failed to create MWI serializer pool. The default SIP pool will be used for MWI\n");
 	}
 
-	solicited_mwi = ao2_container_alloc_hash(AO2_ALLOC_OPT_LOCK_MUTEX, 0, MWI_BUCKETS,
+	mwi_container = ao2_container_alloc_hash(AO2_ALLOC_OPT_LOCK_MUTEX, 0, MWI_BUCKETS,
 		mwi_sub_hash, NULL, mwi_sub_cmp);
-	if (!solicited_mwi) {
-		mwi_serializer_pool_shutdown();
-		ast_sip_unregister_subscription_handler(&mwi_handler);
+	if (!mwi_container) {
+		unload_module();
 		return AST_MODULE_LOAD_DECLINE;
 	}
+	ao2_global_obj_replace_unref(mwi_solicited, mwi_container);
+	ao2_ref(mwi_container, -1);
 
-	unsolicited_mwi = ao2_container_alloc_hash(AO2_ALLOC_OPT_LOCK_MUTEX, 0, MWI_BUCKETS,
+	mwi_container = ao2_container_alloc_hash(AO2_ALLOC_OPT_LOCK_MUTEX, 0, MWI_BUCKETS,
 		mwi_sub_hash, NULL, mwi_sub_cmp);
-	if (!unsolicited_mwi) {
-		mwi_serializer_pool_shutdown();
-		ast_sip_unregister_subscription_handler(&mwi_handler);
-		ao2_ref(solicited_mwi, -1);
+	if (!mwi_container) {
+		unload_module();
 		return AST_MODULE_LOAD_DECLINE;
 	}
+	ao2_global_obj_replace_unref(mwi_unsolicited, mwi_container);
+	ao2_ref(mwi_container, -1);
 
 	ast_sorcery_observer_add(ast_sip_get_sorcery(), "contact", &mwi_contact_observer);
 	ast_sorcery_observer_add(ast_sip_get_sorcery(), "global", &global_observer);
@@ -1571,7 +1582,8 @@ static int load_module(void)
 	if (!ast_sip_get_mwi_disable_initial_unsolicited()) {
 		create_mwi_subscriptions();
 		if (ast_test_flag(&ast_options, AST_OPT_FLAG_FULLY_BOOTED)) {
-			ast_sip_push_task(NULL, send_initial_notify_all, NULL);
+			ast_sip_push_task(ast_serializer_pool_get(mwi_serializer_pool),
+				send_initial_notify_all, NULL);
 		} else {
 			struct stasis_subscription *sub;
 
@@ -1581,27 +1593,16 @@ static int load_module(void)
 		}
 	}
 
-	return AST_MODULE_LOAD_SUCCESS;
-}
-
-static int unload_module(void)
-{
-	ast_sorcery_observer_remove(ast_sip_get_sorcery(), "global", &global_observer);
-	ast_sorcery_observer_remove(ast_sip_get_sorcery(), "contact", &mwi_contact_observer);
-
-	ao2_callback(unsolicited_mwi, OBJ_UNLINK | OBJ_NODATA | OBJ_MULTIPLE, unsubscribe, NULL);
-	ao2_ref(unsolicited_mwi, -1);
-	unsolicited_mwi = NULL;
-
-	ao2_cleanup(solicited_mwi);
-
-	mwi_serializer_pool_shutdown();
-
-	ast_sip_unregister_subscription_handler(&mwi_handler);
+	if (!mwi_serializer_pool) {
+		/*
+		 * If the mwi serializer pool was unable to be established then the module will
+		 * use the default serializer pool. If this happens prevent manual unloading
+		 * since there would now exist the potential for a crash on unload.
+		 */
+		ast_module_shutdown_ref(ast_module_info->self);
+	}
 
-	ast_free(default_voicemail_extension);
-	default_voicemail_extension = NULL;
-	return 0;
+	return AST_MODULE_LOAD_SUCCESS;
 }
 
 AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "PJSIP MWI resource",