"Break-in" is special service in trandition PBX. It can be used to break in an exist call session. In call center, there are often used by operators. For example, user A establishs call connection with user B, user C can break in their connection and make conference with A and B.In this scenario, C is an operator.
"Overstep" is another special service which is used to reject "break-in". As we know, not all sessions can be broken in. For example, you can not break in your boss' sessions. If the user has "overstep" right, operators cannot break in his/her sessions.
In MSS, if a user wants to break in other's sessions, it should have "break-in" right and the user can dial prefix "*75*" to break in target user's session. Below is the format:
*75*+target user number
For example, if the user wants to break in the session of local user 100, he/she can dial "*75*100".