I have 1 polycom model is vtx 1000 analog conference station connected to UC520 FSX port. The conference station can make 1 to 1 call without any problem but it can't conference for 3 party if the conference initial by conference station. Once I press the conf buttom on conference station I can see flash then it can't get second line. In my CME i already specify dual line for the ephone-DN that assign to conference station. If the conference call not initial by conference station, let say I use my mobile phone call the conference station once pick up, I press conference buttom on conference station then I can get the second line and get 1 more party join the conference. However it it support max 3 party conference.
1. Does the analog conference work on this way?
2. Is there any wrong in my configuration that cause conference station can initial conference call?
3. What to configure so I can let my conference station get the second line?