Architect Flow Fails to Parse SIP Headers from BYOC Trunks in APAC Region

Architect & Flows
1

My configuration keeps failing…

We are currently troubleshooting a critical issue where specific SIP headers appended by our primary carriers in the Asia Pacific region are being stripped or malformed before reaching the Architect flow logic. This is impacting our ability to route inbound calls based on custom carrier-provided metadata, which is essential for our analytics reporting and downstream integration workflows.

The environment consists of 15 BYOC trunks configured across multiple APAC sub-regions. The primary carrier utilizes a custom header, X-Carrier-Source-ID, to identify the originating network segment. In the Architect flow, we have a Set Variable action configured to parse this header using the standard {{system.call.from.sip_headers.X-Carrier-Source-ID}} syntax. However, the variable consistently returns null or an empty string, despite the header being present in the raw SIP INVITE captured via Wireshark on the edge.

We have verified the following:

  1. The BYOC trunk configuration in Genesys Cloud explicitly allows custom SIP headers in the security settings.
  2. The carrier has confirmed they are sending the header in every INVITE.
  3. The Architect flow version is deployed and active (v14.2).
  4. Other standard headers like X-Cisco-Dialplan are parsed correctly.

Interestingly, this issue appears isolated to trunks routed through our Singapore and Jakarta points of presence. Trunks in Sydney and Tokyo process these headers without issue. This suggests a potential regional routing anomaly or a specific SIP proxy behavior within the APAC infrastructure that is filtering non-standard headers before they reach the media servers.

Has anyone encountered similar header stripping issues with specific APAC carriers? Are there known limitations with how Genesys Cloud processes custom SIP headers in these specific geographic regions? We are considering implementing a workaround using DTMF detection or ANI mapping, but losing the structured header data significantly degrades our real-time analytics capabilities.

Thank you for the assistance.

2

This looks like a region-specific SIP parsing quirk rather than a standard Zendesk migration issue.

"settings": {
 "sip_headers": {
 "preserve_custom": true
 }
}

Check if your BYOC trunk settings in APAC have preserve_custom enabled, as EU defaults might differ.