From your description, it sounds like the midwifes have 3CX phones. The concern is when they are already on a phone call they need to hear a beep indicating another call is coming in. As
@ConceptsWeb has mentioned, this is not possible with queues or ring groups. But it is possible for a direct call.
What if we used a CFD to determine where / when to route calls rather than a queue? True, the CFD would need to have access to a schedule to know where to route calls. It would not be as simple or as flexible as allowing midwives to log in/out of queues as needed, but I assume someone is managing the work schedules and could update a calendar. We do something similar with our
3CX On Call Manager tool.
Alternatively, perhaps you could create a web page where midwives could flip a switch saying whether they are available (sounds a lot like a queue but is not). That would also make it pretty simple to display on the web page a list of midwives and their current availability.
Here is how the call routing would work. First, route inbound calls to the CFD. The CFD could look up who is available (from a list or a calendar), then route the call to the appropriate extension. Since this is a direct call, the midwife should hear a beep if they are already on a call. The bigger challenge, perhaps, is what to do if the midwife doesn't answer the call. I suppose they could set their destination on no answer or set their presence to away and in either case have calls forwarded a queue.
On the other hand, you could initially use a queue and if nobody answers the call, have the call forwarded to a voicemail box. If using voicemail is a reasonable
backup option to the queue, then many, many more options are possible. In the case of our 3CX On Call Manager (OCM), a patient could leave a voicemail in the designated on-call voicemail box, and OCM will look at the schedule to see who is on call, and call that person on the phone, send an email, and send a SMS text. It will do this repeatedly and then escalate to additional midwifes (again based on a schedule).
OCM does provide a web-based calendar that the midwives can use to essentially "log in/out" based on their availability. And you can schedule up to 30 levels of escalation with an unlimited number of backup midwifes at each level. But this is all dependent on the use of voicemail.