Sorry to disagree but I don't see how the service provider has anything to do with this other than maybe CPC. The problem is user error as I explained above. True, changing ALS to intercom first will stop this from happening but every extension programmed that way will have to press an idle line button instead of just picking up the handset to make an outgoing call. So you just trade one problem for another.

The solution here is proper user training.

-Hal

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