2.3.1 Call states at the user side of the interface

The states which may exist on the user side of the user-network interface are defined in this subclause.

2.3.1.1 Null state (U0)

2.3.1.2 Call initiated (U1)

2.3.1.3 Overlap sending (U2)

2.3.1.4 Outgoing call proceeding (U3)

2.3.1.5 Call delivered (U4)

2.3.1.6 Call present (U6)

2.3.1.7 Call received (U7)

2.3.1.8 Connect request (U8)

2.3.1.9 Incoming call proceeding (U9)

2.3.1.10 Active (U10)

2.3.1.11 Release request (U19)