Samsung OS100. Lines are answered by voice mail/auto-attendant. Individual line keys on all phones. When auto-attendant is transferring an outside call to an extension, the line key on the phones is red, customer cannot pick up line at another phone. Is there a way to have the line flash so the customer can pick up the line on another phone? I have checked programming and nothing is jumping out at me.

If the system hasn't been changed you should be able to pick up a ringing call by dialling 65+ extension number

Line keys won't flash on a transfer.

If the call is going to a group you can program a group pickup key which will flash whenever a call rings to that group.