Well NO, I can not explain the logic that drove the designers of a system that was developed over 23 years ago.
And, most likely, none of them are around for me to ask either.
But I could probably rationalize the logic, based on the fact that at the time it was developed, (circa 1984 or so) there was nothing like it in the market at all, and
BELL LABS thought it was filled with
(AT THE TIME) KICK XSS Features.
This
(FP2) was only the 3rd iteration of the ORIGINAL Electronic Key System known as the MERLIN Platform.
There probably was some feed back from the users of the Plain Jane Merlin 206, 410 & 820, and the users of the FP1 for those same systems that drove the design of the FP2.
That was the way the process worked, Marketing would provide their best guess as to what they could sell, based on marketing research (surveys), Bell Labs would design it, Western Electric (at the time) would produce it, and once the product was delivered, it would be evaluated as to how well it met customer needs and what the customers thought could improve it. (more surveys, of course)
Just like most any other product being developed and marketed today.
But realize, this product has been a work in progress from the original Merlin 206, 410 & 830
(crude but effective PLAIN JANE Key Systems) to the MAGIX Release 4.
(A very sophisticated Hybrid PBX system with features the designers of the 206 had NEVER HEARD OF OR THOUGHT OF)
You must know this as well, the MERLIN 206 was the FIRST PRODUCT the "DIVESTED" Bell System designed to be
SOLD, rather than
LEASED, after the
BREAK-UP of the Bell System.
But, then again, I'd be willing to bet you have no idea of what I am talking about in regards to that matter, (
DIVESTITURE) considering it also happened about 23 years ago. As of this day and age, few people do.
Really and truly, your best bet would be to get a
MERLIN PLUS with the latest FP, as I stated before.
That should meet your needs just fine, with very few
BUCK$ out of your pocket.
That way, you can use the phones you have and you would gain a great feature called
BUSYBUSTER, which you will find that very few, if any systems provide.