LiveWire, give Mike Sandman a call....
http://www.sandman.com, he will likely have a diagnosis and fix for you.
For a couple of wild guesses: either the stutter tone on the VOIP line isn't recognized by the ATA/phone system or isn't working reliably. You don't provide any details, but I suspect your setup is an ATA box between the VOIP line(s) and KX-TA824.
I had an issue where my DoorKing gate phone wouldn't ring a VOIP PBX, although CO lines would. A Sandman Line Voltage Booster II fixed that problem - not because the ring voltage was too low but because the waveform wasn't 'precise' enough to cause the VOIP PBX to recognize it. Your stutter tone issue might be similar - the ATA version of it may not be compatible with the Panny.
Hope this is remotely useful
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