I’m completely stumped as to why our BYOC trunk connections are dropping with a 488 Incompatible Codec error specifically during peak scheduling windows when agent adherence is technically at 98%. We are running Genesys Cloud v2024.1.0 and have configured our SIP trunks to negotiate G.711 ulaw as the primary codec, with G.729 as the fallback. The WFM schedule publishes without issue via the /api/v2/wfm/scheduling/v2/schedules endpoint, and agent availability states sync correctly to the routing engine. However, when a call routes to an agent who has just completed a shift swap or has a complex time-off pattern that affects their logged-in state, the SIP INVITE from the BYOC edge fails. The trace shows the SDP offer contains only G.729, but the Genesys Cloud side seems to reject it, responding with 488. This is weird because our media settings explicitly allow G.729. I have checked the agent’s device profile and the softphone settings are default. The issue seems correlated with the WFM data feed updating the agent’s status from ‘Available’ to ‘On Break’ or ‘Not Ready’ mid-negotiation, possibly causing a race condition in the media path setup. We are using the v2 Python SDK to pull schedule data, and the timestamps match the SIP failure logs within a 2-second window. Is there a known issue with codec negotiation when agent state changes rapidly due to WFM triggers? We have tried increasing the SIP timeout values in the edge configuration, but that only delays the failure. The error logs on the BYOC side show ‘Remote side sent invalid SDP’, but we are not modifying the SDP manually. This is causing significant call drops for agents who are technically scheduled and available according to the WFM dashboard. Any insights on how WFM state transitions impact SIP media negotiation would be appreciated. We need to ensure that schedule adherence events do not interfere with the underlying telephony stack.
The docs actually state that codec negotiation failures on BYOC trunks are rarely about the WFM schedule itself, but rather about how the platform handles concurrent session limits during peak adherence windows. When agent adherence hits 98%, the signaling load spikes. If the SIP trunk provider is not configured to handle the burst of INVITE requests efficiently, it may default to a stricter codec check or drop the session before full negotiation occurs.
For digital channels and voice hybrid environments, I often see this when the S3 export jobs or other background processes are consuming bandwidth that impacts the signaling path stability. However, the primary fix is usually in the SIP trunk configuration on the provider side, not Genesys.
Check if the provider is sending a 488 before the full SDP exchange is complete. You might need to adjust the sdp timeout values in your trunk settings. Also, verify that the Genesys Cloud side is strictly enforcing the G.711 ulaw preference. Here is a snippet of how the trunk configuration should look in the API payload to ensure strict ordering:
{
"name": "BYOC-Trunk-Primary",
"type": "sdp",
"codecs": [
{
"name": "G711ULAW",
"order": 1
},
{
"name": "G729",
"order": 2
}
]
}
If the order is correct, the issue might be a race condition where the WFM schedule change triggers a re-registration or state update that momentarily destabilizes the trunk session. Try isolating the trunk traffic by disabling non-essential integrations during the peak window to see if the 488 errors cease. This helps determine if it is a bandwidth contention issue or a pure SIP negotiation failure.