K.1 Common information elements.

H.4 Service or option not implemented class

H.7 Interworking class

H.5 Invalid message (e.g., parameter out of range) class

H.6 Protocol error (e.g., unknown message) class

H.3 Service or option not available class

H.2 Resource unavailable class

H.1 Normal class

G.5 Causes related to invalid messages

G.4 Causes related to nature of request