Diameter Result-Code 4012 in 10 Seconds

Quick one from a Telegram question today:

Result-Code 4012 = DIAMETER_CREDIT_LIMIT_EXCEEDED

This is the OCS telling the PGW/UGW: “this subscriber has no credit left.” It’s not a fault — it’s a business decision.

What to check:

• Is it all subscribers or just one? → If all: OCS balance pool exhausted or rating config broken.
• Just one? → Subscriber out of quota. Normal for prepaid.
• Comes back right after top-up? → Working as designed.

Wireshark filter to isolate it:

diameter.result_code == 4012

Don’t waste time on GTP tunnels when the OCS already said “no money.” Check the result-code first.