Volusia County Schools does this mostly to systems that are failing or are aging (primarily older Autocall systems from the late 80s-early 90s, but also newer systems from FCI and Fire-Lite). Their administration center is getting a new Notifier NFS-320 system to replace their older Pyrotronics System, but they might be keeping some of the pulls and newer Siemens and Gentex NAs. Surprisingly enough, my first elementary school replaced theirs sometime after I left (MTs, MASS, 2901-9838s on 2903s with Commander 3s).