Hello,
this won't work. Actually, many things that your customer wants will not work.
First, to make all phones ring at once, you do not create multiple ephone-dn with the same number. Doing so will have the calls go round robin across ephone-dn.
The way to do it, is to assign the same ephone-dn to multiple phones, in overlay on a button if necessary.
The next problem you will find, is that because ephone-dn have a maximum of two lines, you cannot handle more than two calls to the same number. Moreover, when a phone takes a call for the an ephone-dn, it will "become" hat ephone-dn.
The workaround is to setup a chain of ephone-dn that are single-line, each one having "call forward busy" to the next, each with a different number. All these ephone-dn will be assigned to the ephones via button overlay in the group.
This should satisfy the first requisite, but will not give them a queue of calls.
Note: life would be much easier with a regular hunt-group. If you set the timeout shorts, and give them login/logout buttons, the net effect is better than "ring blast".
They would be able to see how many calls there are in queue, get statistics, etc. understand this is not the method they are used to have. But you can try.
