When an X.25 call is cleared, a response similar to below could be provided to you:
| X.25 Diagnostic Codes |
| Code | Description |
| 001 | Invalid P (S) (01h) |
| 002 | Invalid P (R) (02h) |
| 016 | Packet type invalid (10h) |
| 017 | For state r1 (11h) |
| 018 | For state r2 (12h) |
| 019 | For state r3 (13h) |
| 020 | For state p1 (14h) |
| 021 | For state p2 (15h) |
| 022 | For state p3 (16h) |
| 023 | For state p4 (17h) |
| 024 | For state p5 (18h) |
| 025 | For state p6 (19h) |
| 026 | For state p7 (1Ah) |
| 027 | For state d1 (1Bh) |
| 028 | For state d2 (1Ch) |
| 029 | For state d3 (1Dh) |
| 032 | Packet not allowed (20h) |
| 033 | Unidentifiable packet (21h) |
| 034 | Call on one-way logical channel (22h) |
| 035 | Invalid packet type on a permanent virtual circuit (23h) |
| 036 | Packet on unassigned logical channel (24h) |
| 037 | Reject not subscribed to (25h) |
| 038 | Packet too short (26h) |
| 039 | Packet too long (27h) |
| 040 | Invalid general format identifier (28h) |
| 041 | Restart or registration packet with nonzero in bits 1 to 4 of octet 1, or bits 1 to 8 of octet 2 (29h) |
| 042 | Packet type not compatible with facility (2Ah) |
| 043 | Unauthorized interrupt confirmation (2Bh) |
| 044 | Unauthorized interrupt (2Ch) |
| 045 | Unauthorized reject (2Dh) |
| 048 | Time expired (30h) |
| 049 | For incoming call (31h) |
| 050 | For clear indication (32h) |
| 051 | For reset indication (33h) |
| 052 | For restart indication (34h) |
| 053 | For call deflection (35h) |
| 064 | Call setup, call clearing, or registration problem (40h) |
| 065 | Facility/registration code not allowed (41h) |
| 066 | Facility parameter not allowed (42h) |
| 067 | Invalid called DTE address (43h) |
| 068 | Invalid calling DTE address (44h) |
| 069 | Invalid facility/registration length (45h) |
| 070 | Incoming call barred (46h) |
| 071 | No logical channel available (47h) |
| 072 | Call collision (48h) |
| 073 | Duplicate facility requested (49h) |
| 074 | Nonzero address length (4Ah) |
| 075 | Nonzero facility length (4Bh) |
| 076 | Facility not provided when expected (4Ch) |
| 077 | Invalid CCITT-specified DTE facility (4Dh) |
| 078 | Maximum number of call redirections or call deflections exceeded (4Eh) |
| 080 | Miscellaneous (50h) |
| 081 | Improper cause code from DTE (51h) |
| 081 | Not aligned octet (52h) |
| 082 | Inconsistent Q bit setting (53h) |
| 083 | NIU problem (54h) |
| 112 | International problem (70h) |
| 113 | Remote network problem (71h) |
| 114 | International protocol problem (72h) |
| 115 | International link out of order (73h) |
| 116 | International link busy (74h) |
| 117 | Transit network facility problem (75h) |
| 118 | Remote network facility problem (76h) |
| 119 | International routing problem (77h) |
| 120 | Temporary routing problem (78h) |
| 121 | Unknown called DNIC (79h) |
| 122 | Maintenance action (may apply to maintenance action within a national network) (7Ah) |
| 128-255 | CCITT--Reserved for network-specific diagnostic information (80h-FFh) |
