ITU Q.850:1998
ITU Q.850:1998 Usage Of Cause And Location In The Digital Subscriber Signalling System No. 1 And The Signalling System No. 7 Isdn User Part Specifies the format, encoding and semantics of cause information elements/parameters and the usage of the location field, in the Digital Subscriber Signalling System No. 1 and Signalling System No. 7