Got a customer with an ACS R6 with 18D sets. Loud squeal starts when adding a line for conference. 1 - talking on first line; 2 - press Conf and dial second party; 3 - Press Conf to establish conference and loud squeal starts.
I have never seen this, but I suspect high loop current. A friend has borrowed my VOM so I couldn't test loop current, but have any of you encountered this before? I will return tomorrow with VOM.

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