OK, I got my GXP2140 yesterday afternoon and have been playing with it. I think I understand it now, and I also now understand Marcin’s explanation.
I set up my phone with two registered accounts, each assigned to an MPK. In Line mode I can do a three-party conference call (me, MPK1, MPK2) but if I try to add a fourth party it puts the third party on hold and lets me dial, but when I try to connect it doesn’t and instead takes the third party off hold. I think this is confusing, and probably not what it should do.
However in Account mode I can add a fourth party just fine.
I don’t understand what else Line/Account mode does, and don’t understand why the choice even exists. In other words, I don’t understand what you give up if you choose Account mode. I also don’t understand side effects, like what CID gets reported if there are two accounts with different CIDs and you are in Line mode.
But, I now know how to fix my customer’s complaint, which was that conference calls stopped working when I took the confusing (and I thought unnecessary) second extension off each phone.
Thanks to all…