Let me ask this a different way:
Does anyone have a sound powered phone handset or headset that has a bridge pressure-proof type plu? If so, would you please copy any info from the plug that you can find, ie., manufacturer, part no. FSN, etc. It would be a big help to us on Torsk so that we can acquire a couple of the plugs needed to restore our sound-powered phone system.
See the attached photo.
Thanks!