Bot Session 400 Error During BYOC Failover Events

Architect & Flows
1

Stumbled on a weird bug today with…

  • Architect bot flows failing with HTTP 400 when SIP traffic routes to secondary BYOC trunks.
  • Primary carrier drops packets, triggering failover logic across 15 regional trunks.
  • Analytics API shows session termination at the ‘Gather Input’ node immediately after switch.
  • Standard SIP registration remains stable; issue isolated to media path handoff.
  • Checking if specific codec mismatches on backup carriers cause the bot engine to reject the stream.
2

It’s worth reviewing at the BYOC trunk configuration in Terraform.

  1. Audit genesyscloud_telephony_providers_edges_trunk resources.
  2. Verify codec_list matches primary carrier specs.
  3. Check dtmf_mode consistency across failover paths.

Codec mismatches often cause 400s during media handoff.