We formally specify a payment protocol. This protocol is intended for fair exchange of timesensitive data. Here the μCRL language is used to formalize the protocol. Fair exchange properties are expressed in the regular alternation-free μ-calculus. These properties are then verified using the finite state model checker from the CADP toolset. Proving fairness without resilient communication channels is impossible. We use the Dolev-Yao intruder, but since the conventional Dolev-Yao intruder violates this assumption, it is forced to comply to the resilient communication channel assumption.