"restrict an slt phone from calling one ext. in a system"
This sounds more like a Human Resources issue than a programming issue.
I believe you might be thinking of a Hotel/Motel Feature:Intercom Call Restriction
"ECS may be programmed to restrict guest rooms from calling each other to
eliminate prank calls. Guests may still make intercom calls to the
Hotel/Motel's administrative extensions." pages 138 and 347
This tells me a few things.
- This only applies to systems with Hotel/Motel feature packet installed.
- The Owner's manual doesn't show how to program the feature therefore a certified installer is required
- It appears the this feature applies to ALL intercoms calls to ALL extensions are denied except 0 to the operator.
So I would guess that the answer is no, you cannot deny a telephone from calling one extension.http://www.btsnp.com/wp-content/uploads/2016/03/Iwatsu-ECS-Owners-Manual.pdf
The only other way is to get messy with putting extension in different Class of Service and deny calling between different COS's. And of course then you have to mess with CO Lines and a plethora of other issues to screw with.
In this Forum we assist with questions that are readily available in the User Guides, Admin Guides and only occasionally Programming guides. Or as the Forum rules state: "As a public and semi-private forum, this information may be used to illegally compromise a system, and that system might be yours!
There is a chance that someone know you system better than I do and may post a solution.