A walk down memory lane:
Project MF. Although not with a live switch, but with an Asterisk server set up to recognize MF tones. Access can be had by dialing C*Net 1-762-2600/2601 or PSTN 630-485-2995. There are also SIP and direct adterisk connections available. See: http://www.projectmf.org/ (http://www.projectmf.org/)
For a Video Demo of Project MF and MF tone control:
https://www.youtube.com/watch?v=hCvu2qgcsVQ#t=271 (https://www.youtube.com/watch?v=hCvu2qgcsVQ#t=271)