I found another way to conference call in more than 4 parties.[/color red]
Establish a three-party conference call:
1. Make or answer the first call.
2. Put the first call on hold.
3. Make or answer the second call.
4. After the second call is connected, press FEATURE 3.
5. Press the line or intercom button of the first held call.
6. Press RLS to end the conference call.
Establish a multi-party conference call (4 or more people):
1. Follow the steps to establish a three-party conference call.
2. Press the Newcall softkey, or press FEATURE 807 or you can also use any other Intercom key.
3. After the fourth call is answered, press FEATURE 3, and press the held line.
4. Put the fourth call on hold and repeat steps 2 and 3 to add more calls to the conference, remember how many channels you have on your PRI or analog lines, as they will fill up quickly.
5. Press RLS to end the conference call.