sundance-communications.com/forum Forums TDM Business Telephone Systems Avaya - Lucent Telephones & Systems IP Office DID selection problem

I have a customer with an IP Office with a pri. When the incoming DID's get really busy most of the calls are on one target line. When another target line rings while the main is ringing I cannot pick up the secondary line, even though it appears on its own button. You can see the line ringing but pressing the button does nothing.
any ideas?