Ring Surpression only working with clamp?


I have recently managed to install the Nuke Opener with my very old STR WF32 intercom. I am really happy that even ring to open works. Thanks to this platform!
While moving I unfortunately lost the clamp for the opener but still managed to get it up and running without.

My old school intercom bell is really haunting and I was hoping to surpress the ringing sound with the opener, unfortunately it is not working.

Now the question is, would ring suppression work if I install the clamp or is it never going to work because the intercom is too old?