A Delay Indicator parameter is contained in CoAP messages to reflect delay tolerance information. The Delay Indicator is leveraged by CoAP Clients and CoAP Servers to improve their behavior such as entering sleep mode to save energy while not violating delay requirements. A timeout mechanism for CoAP Response is enabled by a RESPONSE_Timer based on the Delay Indicator in CoAP ACK. Cancellation of CoAP Requests is enabled by leveraging the delay tolerance information as indicated by Delay Indicator.