Broken choppy ringtone and silence

I have a longstanding problem with incoming calls to my 613-887-XXXX DID. All my other DIDs are fine, call quality with lesnet is fine.
Caller hears a broken ringtone (or broken MOH when I tried that) with long silence periods - quite often the caller thinks they’ve been disconnected and hangs up.
This is I believe caused by some type of silence detection / VAD at the lesnet end. I just discovered that if if I call into this DID and sing or hum into the phone then I hear correct ringing tone with no silence ( I guess as it doesn’t detect silence then it doesn’t chop off the audio).
Is there any way that I can generate some kind of noise to try and force the audio to stay open.
Lesnet’s support says it a problem with these particular DID’s and the switch they run on, strange how the DID always worked fine until the lesnet network upgrade earlier this year. I also have another 613-887-XXXX DID with Link2voip whch works fine

so if they won’t fix their end then I’m stuck with trying to fudge something at my end.
Any ideas, or any other way I could route calls - if I send the DID direct to an extension then the ringtone is fine, but I need the call to go to a ringgroup to call first office then home, and cell.
Or does anyone offer porting for Kingston Ontario numbers, 613-887-XXXX