The home operator rejected roaming for this subscriber (DIAMETER_ERROR_ROAMING_NOT_ALLOWED) — almost always means there's no active roaming agreement between the networks, or the subscriber is explicitly restricted.
In the Result-Code or Experimental-Result-Code AVP of a Diameter answer (S6a, S6d, Gx, Gy, Cx…).
Careful: 5004 also means DIAMETER_INVALID_AVP_VALUE. In Diameter the base protocol (Result-Code) and 3GPP applications (Experimental-Result-Code) reuse the same numbers, so read the name, not just the number.
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