Testing a telecommunication protocol often requires protocol log analysis. A protocol log is a sequence of messages with timestamps. Protocol log analysis involves checking that the content of messages and timestamps are correct with respect to the protocol specification. We model the protocol specification using constraint programming (MiniZinc), and we present an approach where a constraint solver is used to perform protocol log analysis. Our case study is the Public Warning System service, which is a part of the Long Term Evolution (LTE) 4G standard.