Can a 3rd or 4th user join a 3-way conference if there are already two users on the line with the incoming call?
Unfortunately, the 3-way conferencing feature is limited to 2 dial pads and one outside line. “Line in Use” appears in the displays of the rest of dial pads registered to the same base. Though the other dial pads can intercom each other during this time, they will not be able to answer or make outside calls.