MorganS:
Yes, that looks like it will do the job.Connecting to old phones is somewhat tricky. The phones run on 48V DC and if you want to make it ring then there's even more volts required. It is probably best to rip out all of the electronics in the phone and put in your own speaker and microphone.
Even more complications. The regular telephone mike is a carbon mike. Google that! Needs a DC voltage and a transformer to be workable at all.
Paul