diff --git a/services/tunnelbroker/src/Constants.h b/services/tunnelbroker/src/Constants.h
index 2ee2b8d5c..2f8285563 100644
--- a/services/tunnelbroker/src/Constants.h
+++ b/services/tunnelbroker/src/Constants.h
@@ -1,67 +1,68 @@
 #pragma once
 
 #include <cstdlib>
 #include <regex>
 #include <string>
 
 namespace comm {
 namespace network {
 
 // AWS DynamoDB
 const size_t DYNAMODB_MAX_BATCH_ITEMS = 25;
 const size_t DYNAMODB_BACKOFF_FIRST_RETRY_DELAY = 50;
 const size_t DYNAMODB_MAX_BACKOFF_TIME = 10000; // 10 seconds
 
 const std::string DEVICE_SESSIONS_TABLE_NAME = "tunnelbroker-device-sessions";
 const std::string DEVICE_SESSIONS_VERIFICATION_MESSAGES_TABLE_NAME =
     "tunnelbroker-verification-messages";
 const std::string DEVICE_PUBLIC_KEY_TABLE_NAME = "tunnelbroker-public-keys";
 const std::string MESSAGES_TABLE_NAME = "tunnelbroker-messages";
 
 // Sessions
 const size_t SIGNATURE_REQUEST_LENGTH = 64;
 const size_t SESSION_ID_LENGTH = 64;
 const size_t SESSION_RECORD_TTL = 30 * 24 * 3600; // 30 days
 const size_t SESSION_SIGN_RECORD_TTL = 24 * 3600; // 24 hours
 const std::regex SESSION_ID_FORMAT_REGEX(
     "[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}");
 
 // AMQP (RabbitMQ)
 const std::string AMQP_FANOUT_EXCHANGE_NAME = "allBrokers";
 // Message broker queue message TTL
 const size_t AMQP_MESSAGE_TTL = 300 * 1000; // 5 min
 // queue TTL in case of no consumers (tunnelbroker is down)
 const size_t AMQP_QUEUE_TTL = 24 * 3600 * 1000; // 24 hours
 // routing message headers name
 const std::string AMQP_HEADER_FROM_DEVICEID = "fromDeviceID";
 const std::string AMQP_HEADER_TO_DEVICEID = "toDeviceID";
 const std::string AMQP_HEADER_MESSAGEID = "messageID";
 
 const size_t AMQP_RECONNECT_ATTEMPT_INTERVAL_MS = 3000;
 const size_t AMQP_RECONNECT_MAX_ATTEMPTS = 10;
 
 // DeviceID
 // DEVICEID_CHAR_LENGTH has to be kept in sync with deviceIDCharLength
 // which is defined in web/utils/device-id.js
 const size_t DEVICEID_CHAR_LENGTH = 64;
 // DEVICEID_FORMAT_REGEX has to be kept in sync with deviceIDFormatRegex
 // which is defined in web/utils/device-id.js
 const std::regex DEVICEID_FORMAT_REGEX(
     "^(ks|mobile|web):[a-zA-Z0-9]{" + std::to_string(DEVICEID_CHAR_LENGTH) +
     "}$");
+const size_t DEVICE_ONLINE_PING_INTERVAL_MS = 3000;
 
 // Config
 const std::string CONFIG_FILE_DIRECTORY_ENV_VARIABLE =
     "TUNNELBROKER_CONFIG_FILE_DIRECTORY";
 const std::string DEFAULT_CONFIG_FILE_DIRECTORY =
     std::string(std::getenv("HOME")) + "/tunnelbroker";
 const std::string CONFIG_FILE_NAME = "tunnelbroker.ini";
 const std::string SANDBOX_CONFIG_FILE_NAME = "tunnelbroker-sandbox.ini";
 
 // DeliveryBroker
 const size_t DELIVERY_BROKER_MAX_QUEUE_SIZE = 100;
 // Database messages TTL
 const size_t MESSAGE_RECORD_TTL = 300 * 24 * 60 * 60; // 300 days
 
 } // namespace network
 } // namespace comm