Essentially, I'm trying to figure out why 3CXPhone doesn't support multiple simultaneous accounts being registered. Here's the scenario: Client is running essentially two different organizations. Incoming calls go into one of two different queues, based on the DID number called (they're straight SIP trunks). They've got Yealink phones. Each user has three separate accounts/extensions, each assigned to a button on the phones. If a call comes in on button 1, they know it is a "direct" call, if it comes in on button 3, they know it is a call for organization "A" and if a call comes in on button 4, they know it is a call for organization "B." Pressing each button for outgoing calls allows using different outbound Caller IDs. I know the "workaround" using a single account/extension is to simply use the incoming Caller ID to show which queue the call came from, and to dial a prefix (9, 8, etc.) for outgoing calls. The problem is that each person might be handling one, or the other, or both of the queues. If you dial *62 to log into the queues, if a single account is a member of multiple queues, you'll be logged into ALL of them. No way that I know of to specify from a physical phone. Which is why I've got three separate accounts on different buttons; select the account that belongs to the queue you want to log into and then dial *62 and you'll be logged into THAT queue and not the other. But 3CXPhone doesn't seem to allow doing this. If I create multiple accounts, you can't have those multiple accounts all registered at the same time. So there's no way to have each account be a member of only one queue but be able to answer calls from both. I don't remember offhand whether you can log into ONE queue of which you're a member with 3CXPhone or whether - like a physical phone - it logs you into ALL queues associated with that account. Even if so, that doesn't help with those people who are using physical phones - or more likely, both. Zoiper (semi-free softphone) DOES seem to allow registering multiple accounts at the same time. Except that the free version doesn't support transfer or hold, and unlike the 3CXPhone, it has no way of knowing the status of other accounts/extensions/queues (even in the paid version, of course).