Network Calculus is a set of mathematical results that enable to derive deterministic bounds for performance measures of queueing systems. Arrival processes in Network Calculus are also modeled by bounds called envelopes. However, empirical envelopes wide-sense increasing but not clearly determined are difficult to use. The article presents a technique based on support vector regression for estimating linear envelopes from empirical ones. An appropriate optimization problem aimed at obtaining delay upper bound is set and solved. An example of calculating linear envelope and corresponding delay and backlog for queueing system of updating I&C database is also presented.