| GTP v1 | 128 | Request Accepted |
| 192 | Non-existent |
| 193 | Invalid message format |
| 194 | IMSI / IMEI not known |
| 195 | Mobile station is detached from the GPRS network. |
| 196 | Mobile station is not responding to the GPRS
network. |
| 197 | Mobile Station refuses connection |
| 198 | GTP version not supported. |
| 199 | No resources available. |
| 200 | Service not supported. |
| 201 | Mandatory IE incorrect |
| 202 | Mandatory IE missing |
| 203 | Optional IE incorrect |
| 204 | System failure |
| 207 | GPRS connection suspended |
| 208 | Authentication failure |
| 209 | User authentication failure |
| 210 | Context not found |
| 211 | All dynamic PDP addresses are occupied |
| 212 | No memory available |
| 213 | Relocation failure |
| 219 | Missing or unknown APN |
| 220 | Unknown PDP address or PDP types |
| 222 | APN access denied no subscription |
| 223 | APN restriction type incompatible |
| 229 | APN congestion |
| GTPv2 | 16 | Request accepted - 2 |
| 64 | Context not found |
| 65 | Invalid message format - 2 |
| 66 | Version not supported by next peer |
| 67 | Invalid length |
| 68 | Service not supported - 2 |
| 69 | Mandatory IE incorrect - 2 |
| 70 | Mandatory IE missing - 2 |
| 72 | System failure - 2 |
| 73 | No resources available - 2 |
| 78 | Missing or unknown APN - 2 |
| 81 | Relocation failure - 2 |
| GTPv2 | 84 | All dynamic addresses are occupied |
| 89 | Service denied |
| 91 | No memory available - 2 |
| 92 | User authentication failed - 2 |
| 93 | APN access denied – no subscription - 2 |
| 94 | Request rejected |
| 96 | IMSI/ IMEI not known - 2 |
| 100 | Remote peer not responding |
| 103 | Conditional IE missing |
| 104 | APN restriction type incompatible - 2 |
| 109 | Invalid peer |
| 110 | Temporarily rejected due to handover |
| 113 | APN congestion - 2 |
