This object sets the signalling for outgoing calls and is used assign incoming calls to interfaces. If set to 0, an ISDN signalling is generated automatically for outgoing calls depending on the values of L1Protocol and L2Protocol. All incoming calls are routed to the interface, when this object is set to 0. Other values are directly used for outgoing calls, independantly of the setting of L1Protocol and L2Protocol. Incoming calls are only assigned to the interface, when the signalling is equal to the value specified here. The possible values are specified elsewhere.