diff --git a/include/asterisk/res_pjsip_pubsub.h b/include/asterisk/res_pjsip_pubsub.h
index f6c6e4109c..d985b9019c 100644
--- a/include/asterisk/res_pjsip_pubsub.h
+++ b/include/asterisk/res_pjsip_pubsub.h
@@ -228,7 +228,21 @@ struct ast_sip_subscription_handler {
 	const char *event_name;
 	/*! The types of body this handler accepts */
 	const char *accept[AST_SIP_MAX_ACCEPT];
-
+	/*!
+	 * \brief Indicates if this handler can be used as a default handler for an event type.
+	 *
+	 * Typically, a SUBSCRIBE request will contain one or more Accept headers that tell
+	 * what format they expect the body of NOTIFY requests to use. However, every event
+	 * package is required to define a default body format type to be used if a SUBSCRIBE
+	 * request for the event contains no Accept header.
+	 *
+	 * If this value is non-zero, then this handler provides the default body format for
+	 * the event package and can handle SUBSCRIBES with no Accept headers present.
+	 * If this value is zero, then this handler provides an alternative body format
+	 * from the default for the event package and cannot handle SUBSCRIBEs with no
+	 * Accept header.
+	 */
+	unsigned int handles_default_accept;
 	/*!
 	 * \brief Called when a subscription is to be destroyed
 	 *
diff --git a/res/res_pjsip_exten_state.c b/res/res_pjsip_exten_state.c
index 483d78b4b5..0144e1cbbb 100644
--- a/res/res_pjsip_exten_state.c
+++ b/res/res_pjsip_exten_state.c
@@ -515,6 +515,8 @@ static void subscription_terminated(struct ast_sip_subscription *sub,
 	send_notify(exten_state_sub, NULL, PJSIP_EVSUB_STATE_TERMINATED);
 }
 
+#define DEFAULT_PRESENCE_BODY "application/pidf+xml"
+
 /*!
  * \internal
  * \brief Create and register a subscription handler.
@@ -534,6 +536,9 @@ static struct ast_sip_subscription_handler *create_and_register_handler(
 
 	handler->event_name = event_name;
 	handler->accept[0] = accept;
+	if (!strcmp(accept, DEFAULT_PRESENCE_BODY)) {
+		handler->handles_default_accept = 1;
+	}
 
 	handler->subscription_shutdown = subscription_shutdown;
 	handler->new_subscribe = new_subscribe;
diff --git a/res/res_pjsip_mwi.c b/res/res_pjsip_mwi.c
index faf0a07b68..e2b9b630dd 100644
--- a/res/res_pjsip_mwi.c
+++ b/res/res_pjsip_mwi.c
@@ -64,6 +64,7 @@ static int mwi_refresh_subscription(struct ast_sip_subscription *sub);
 static struct ast_sip_subscription_handler mwi_handler = {
 	.event_name = "message-summary",
 	.accept = { "application/simple-message-summary", },
+	.handles_default_accept = 1,
 	.subscription_shutdown = mwi_subscription_shutdown,
 	.new_subscribe = mwi_new_subscribe,
 	.resubscribe = mwi_resubscribe,
diff --git a/res/res_pjsip_pubsub.c b/res/res_pjsip_pubsub.c
index 1ccfc1972a..ae31f5c95c 100644
--- a/res/res_pjsip_pubsub.c
+++ b/res/res_pjsip_pubsub.c
@@ -585,6 +585,12 @@ static struct ast_sip_subscription_handler *find_sub_handler(const char *event,
 			continue;
 		}
 		ast_debug(3, "Event name match: %s = %s\n", event, iter->event_name);
+		if (!num_accept && iter->handles_default_accept) {
+			/* The SUBSCRIBE contained no Accept headers, and this subscription handler
+			 * provides the default body type, so it's a match!
+			 */
+			break;
+		}
 		for (i = 0; i < num_accept; ++i) {
 			for (j = 0; j < num_accept; ++j) {
 				if (ast_strlen_zero(iter->accept[i])) {
@@ -620,7 +626,7 @@ static pj_bool_t pubsub_on_rx_subscribe_request(pjsip_rx_data *rdata)
 	struct ast_sip_subscription_handler *handler;
 	RAII_VAR(struct ast_sip_endpoint *, endpoint, NULL, ao2_cleanup);
 	struct ast_sip_subscription *sub;
-	int i;
+	size_t num_accept_headers;
 
 	endpoint = ast_pjsip_rdata_get_endpoint(rdata);
 	ast_assert(endpoint != NULL);
@@ -646,20 +652,21 @@ static pj_bool_t pubsub_on_rx_subscribe_request(pjsip_rx_data *rdata)
 		pjsip_endpt_respond_stateless(ast_sip_get_pjsip_endpoint(), rdata, 489, NULL, NULL, NULL);
 		return PJ_TRUE;
 	}
+	ast_copy_pj_str(event, &event_header->event_type, sizeof(event));
 
 	accept_header = pjsip_msg_find_hdr(rdata->msg_info.msg, PJSIP_H_ACCEPT, rdata->msg_info.msg->hdr.next);
-	if (!accept_header) {
-		ast_log(LOG_WARNING, "Incoming SUBSCRIBE request with no Accept header\n");
-		pjsip_endpt_respond_stateless(ast_sip_get_pjsip_endpoint(), rdata, 400, NULL, NULL, NULL);
-		return PJ_TRUE;
+	if (accept_header) {
+		int i;
+
+		for (i = 0; i < accept_header->count; ++i) {
+			ast_copy_pj_str(accept[i], &accept_header->values[i], sizeof(accept[i]));
+		}
+		num_accept_headers = accept_header->count;
+	} else {
+		num_accept_headers = 0;
 	}
 
-	ast_copy_pj_str(event, &event_header->event_type, sizeof(event));
-	for (i = 0; i < accept_header->count; ++i) {
-		ast_copy_pj_str(accept[i], &accept_header->values[i], sizeof(accept[i]));
-	}
-
-	handler = find_sub_handler(event, accept, accept_header->count);
+	handler = find_sub_handler(event, accept, num_accept_headers);
 	if (!handler) {
 		ast_log(LOG_WARNING, "No registered subscribe handler for event %s\n", event);
 		pjsip_endpt_respond_stateless(ast_sip_get_pjsip_endpoint(), rdata, 489, NULL, NULL, NULL);