When a GTP network element accepts or rejects a GTP request,
the response includes a cause value in the Information Element indicating
the request is accepted or the reason for a rejection.
When a network element such as PGW or GGSN accepts or
rejects a GTP request, it sends a GTP-C response message that includes
a cause value in the cause Information Element (IE) indicating whether
the request is accepted or the reason for rejection. Logs display
the cause value in the GTP cause field.
GTP
Cause Value
Description
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.