Patterns help to improve software quality and reduce development cost by documenting the experience of experts so that good solutions to recurring problems can be reused. In this paper, we propose a pattern-based software development methodology for communication protocols, particularly focusing on the specification and validation of message interactions. For the description of communication protocols, we propose a set of patterns. A complex protocol can be obtained by composing such patterns. To provide confidence in the protocol description, we validate the pattern-based specification by using the SPIN model checker. The validation phase needs model construction for the specification and checks the desired properties of the developing protocol. To show the feasibility of our methodology, we present a case study for the development of a V.76 protocol.