| IP Event | Description | PSTN Cause | |
| Code | |||
|
|
| ||
404 | Not found | No route to destination | 3 | |
486 | User here | User busy | 17 | |
480 Temporarily | No user response | 18 | ||
18 | ||||
unavailable | ||||
| 20 | |||
|
|
| ||
403 | Forbidden | Call Rejected | 21 | |
410 Gone | Number changed | 22 | ||
404 | Not found | Unallocated number | 3 | |
404 | Not found | Unallocated number | 3 | |
484 Address | Address incomplete | 28 | ||
incomplete | ||||
|
| |||
501 | Not | Service or option not implemented | 79 | |
implemented | ||||
|
| |||
404 | Not found | Unallocated number | 3 | |
503 | Service | Service or option unavailable | 63 | |
unavailable | ||||
|
| |||
503 | Service | Service or option unavailable | 63 | |
unavailable | ||||
|
| |||
503 | Service | Service or option unavailable | 63 | |
unavailable | ||||
|
| |||
503 | Service | Service or option unavailable | 63 | |
unavailable | ||||
|
| |||
503 | Service | Service or option unavailable | 63 | |
unavailable | ||||
|
| |||
403 | Forbidden | Bearer Capability not authorized | 21 | |
403 | Forbidden | Service or option not implemented | 79 | |
501 | Not | Service or option not implemented | 79 | |
implemented | ||||
|
| |||
501 | Not | Service or option not implemented | 79 | |
implemented | ||||
|
| |||
503 | Service | Service or option unavailable | 63 | |
Unavailable | ||||
|
| |||
400 | Bad request | Interworking, unspecified | 95 | |
400 | Bad request | Interworking, unspecified | 95 | |
408 | Request | Recovery on Expires timeout | 102 | |
timeout | ||||
|
| |||
400 | Bad request | Protocol error | 111 | |
500 | Internal | Any code other than those listed | 127 | |
server error | above: | |||
| ||||
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