An M/PH/1 queue model with catastrophes is regarded as a generalization of an M/M/1 queue model with catastrophes. Whenever a catastrophe happens, all customers will be cleared immediately and the queuing system is empty. The customers arrive at the queuing system based on a Poisson process and the total service duration has two phases. Transient probabilities of this queuing system is considered by means of practical applications of the modifified Bessel function of the fifirst kind, the Laplace transform and probability generating function techniques.