Hey Kevin - I was familiar with that option and tried it earlier with no luck. It changed the intercom sound but actually made it worse. It made the intercom sound more like to UFO's vs one UFO.

If you can imagine the sound of an old school incoming call on a phone in the UK . Take that sound and stretch it out to become an intercom dial tone . Thats kind of what I hear.

I changed the SD 7134 card which was a UK version to a US version SD card and the sound was the same.

There must be a component on the NS700 base unit that simply transmits a UK sounding intercom . Both cabinets do they same and they are both a UK version.

Thanks Kevin for the suggestion