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Did you ever fix your issue => here <= ?
The issue discussed in this post is fixed in above software versions with above VOIP ticket.
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We are on version 5.5.11526 (which is what this doc mentions should have the fix), and it doesn't appear to have that fix. I have confirmed that disabling call waiting (call.callWaiting.enable="0") fixes the problem with BLF activity. Unfortunately disabling call waiting is not an ideal fix though; because that disables the feature. Currently working with our reseller (NetxUSA) to get a case opened with Polycom.