Question: What does the term "interworking" refer to in the context of mobile originated calls?
Option 1: Interworking between different types of networks within the same environment.
Option 2: Interworking with a network other than PLMN or ISDN, but not including interworking between PLMN and ISDN.
Option 3: Normal case of interworking between PLMN and ISDN.
Option 4: Interworking specifically between PLMN and ISDN networks.
Explanation: In the context of mobile originated calls, "interworking" refers to interactions with a network other than PLMN (Public Land Mobile Network) or ISDN (Integrated Services Digital Network), excluding the normal case of interworking between PLMN and ISDN. This distinction highlights that PLMN and ISDN are considered part of the same environment for this specific context.