Quick troubleshooting view
The remote SIP server temporarily refuses to process calls.
- Carrier maintenance
- Overload
- Channel limit reached
- Read Retry-After
- Check trunk status
- Compare inbound and outbound calls
- Correct only the component confirmed by the checks
- Retest the original symptom after the change
- Escalate with collected evidence when the cause remains unclear
Contextual technician plan
Perform this check and preserve the observed result before changing configuration.
“Read Retry-After” should produce an observation that clearly confirms or rules out “Carrier maintenance”.
If the observation is normal, lower “Carrier maintenance” in the ranking and continue with the next distinct check.
If the observation is abnormal, keep the evidence and investigate “Carrier maintenance” first. Related action: Correct only the component confirmed by the checks.
Perform this check and preserve the observed result before changing configuration.
“Check trunk status” should produce an observation that clearly confirms or rules out “Overload”.
If the observation is normal, lower “Overload” in the ranking and continue with the next distinct check.
If the observation is abnormal, keep the evidence and investigate “Overload” first. Related action: Retest the original symptom after the change.
Perform this check and preserve the observed result before changing configuration.
Compare internal, inbound and outbound calls and note for each one whether audio works in both directions.
If all call directions are bidirectional, the failure is not reproduced on this path; compare the endpoint, network and time window of the original incident.
Repeat the same validation test after the correction and confirm the original symptom is gone. Validate stability before closing the incident.
Before changing configuration, record the current value and a way back.
Escalate with the exact symptom, scope, timestamp and completed checks when the issue remains unresolved.
＋Open the complete detailed guideDetailed explanations and original troubleshooting content.
The remote SIP server temporarily refuses to process calls.
Likely causes
- Carrier maintenance
- Overload
- Channel limit reached
- Route or SBC unavailable
Checks in priority order
- Read Retry-After
- Check trunk status
- Compare inbound and outbound calls
- Use the backup route if designed
When to escalate
Escalate when the failure affects multiple users, a production dependency is unavailable, or logs show a component outside your control. Include timestamps, scope, tests already performed, and the last known working state.