Is there a clean way to handle carrier rejections for high-volume outbound campaigns on BYOC trunks?
We are seeing a spike in 486 Busy Here responses specifically from our Singapore trunk provider. The Architect flow routes calls correctly, but the carrier drops them after the initial INVITE. Is this a trunk capacity issue or a signaling timeout?
trunk_profile: SG_BYOC_01
failover: false
timeout_ms: 5000
The logs show successful registration, yet the call legs fail at the carrier edge. Adjusting the retry logic in the dialer settings hasn’t helped.
If I remember correctly, 486 responses on BYOC trunks usually indicate the carrier is rejecting the call due to missing or incorrect header information in the INVITE, not necessarily a timeout or capacity issue. You should check if the P-Asserted-Identity header matches the registered outbound CNAM exactly.
{
"header_name": "P-Asserted-Identity",
"expected_value": "\"Caller Name\" <+6512345678>"
}
This is caused by a mismatch between the flow configuration and the carrier’s strict validation rules for identity headers. While the previous suggestion regarding the P-Asserted-Identity header is technically accurate, it often overlooks the specific formatting requirements imposed by Asian carriers, which frequently enforce stricter CNAM validation than their North American counterparts.
In the Architect flow, ensure the outbound call block explicitly maps the caller ID number to a verified trunk line. If the flow uses a generic number that does not match the exact provisioning on the SG_BYOC_01 trunk, the carrier will reject the INVITE with a 486 Busy Here response. This is a common configuration oversight when scaling digital queues alongside voice campaigns.
Refer to the platform documentation on outbound call routing for detailed header mapping guidelines: https://developer.genesys.cloud/api-docs/outbound-calls. Verify that the From header in your SIP trace matches the registered CNAM precisely.