Troubleshooting
SIP error code translator
Select a SIP response code and walk through an interactive decision tree. Get platform-specific fixes for Asterisk, Kamailio, and 3CX.
488 Not Acceptable Here
Codec or media negotiation failed. The most common cause is SDP mismatch between endpoints.
- · No common codec between endpoints
- · G.729 license missing
- · DTMF mode mismatch
- · SRTP required but not offered
Step 1
Where does the 488 occur?
How it works
Three steps to results
- 01
Select the error code
Choose from 12 common SIP codes: 403, 404, 408, 480, 486, 488, 491, 500, 503, 603, 604, 606.
- 02
Answer diagnostic questions
The decision tree narrows down the root cause based on your call scenario — trunk, internal, inbound, or outbound.
- 03
Apply platform fixes
Get step-by-step remediation for Asterisk, Kamailio, or 3CX with config file references and CLI commands.
FAQ
Frequently asked questions
Common questions about this tool and how it fits into your VoIP security workflow.
Contact support →488 means codec negotiation failed. Check that your trunk allow= list includes codecs the carrier accepts (usually ulaw/alaw). Use this tool's decision tree for step-by-step Asterisk pjsip.conf fixes.
Getting 403 from your carrier?
Check if your IP is flagged in our honeypot database.
A compromised PBX sending spam can cause carrier blocks. Cross-reference your IP against 214 active SIP honeypots.