Causality is one of the important properties for quality check of network parameters. Discrete Hilbert Transform (DHT) based delay causality checking and/or enforcing method is discussed in the present paper. DHT based causality checking/enforcing algorithm is known but is not widely used in applications. Comparison analysis between DHT based delay causality and other causality checking algorithms is given and advantage of the DHT based algorithm is discussed. Front delay is used for delay causality definition. Several methods for front delay estimation are suggested. Delay causality is checked and enforced for different test cases using the proposed methodology.