Are you looking for the switch itself for a collectors piece? Or are you needing a modern electronic replacement for it??
If the latter, check out their site:
http://www.okrailsignals.com/Maybe give them a call. They may be able to steer you in the right direction!!
Check out the attached video of mine. I had it wired so if the phone rang, it ran a 15 second timer relay so I knew the phone was ringing if I was outside. LOL But, we got rid of the landline a while ago. :-( I'll turn it on once in a while to wake up the neighbors though! (Hey, Gotta stop the wasps from making a hive in the bell too!!) LOL
Hope this helps!