SIP trunk registration fails during wfm schedule publish window

Is it possible to configure the sip trunk to ignore the burst of outbound calls triggered by the wfm schedule publish job? we are seeing a massive spike in 408 request timeout errors on our primary sip trunk every monday at 06:00 ct. this is exactly when the agent schedule gets published and the system starts pushing notifications or making test calls to verify agent availability. the trunk provider is saying we are exceeding our concurrent session limit but our historical data shows normal usage levels at that time.

i checked the architect logs and see a lot of failed outbound interactions originating from the wfm integration flow. the error code is specifically 408 on the sip stack but the architect flow shows the call attempt was initiated successfully. it seems like the sip trunk is dropping the call before it even rings the agent.

we have tried increasing the trunk capacity but that just delays the issue. the real problem is the timing. the wfm publish job sends a lot of requests in a short window and it looks like the sip stack gets overwhelmed. is there a way to throttle the outbound calls from the wfm module or add a delay between each call attempt? i dont want to break the schedule adherence tracking but the current setup is causing a lot of missed calls and agent complaints.

also noticed that the /api/v2/wfm/scheduling/schedules endpoint returns 200 ok but the subsequent sip calls fail. this suggests the issue is not with the wfm api itself but with the telephony layer handling the load. any ideas on how to decouple the sip trunk from the wfm publish process? maybe using a queue or async processing for the outbound calls? we are using genesys cloud version 2023.10 and the sip trunk is configured with standard iax2 settings. the problem started after we increased the number of agents in the schedule. before that it was fine. now with 500+ agents publishing at once the trunk chokes. need a solution asap because next monday is peak season for us.

This happens because the platform’s default retry logic colliding with your trunk’s concurrent session limit. The WFM publish job triggers a burst of availability checks that look like outbound calls to the SIP provider. You need to adjust the max_concurrent_sessions in your trunk config or stagger the WFM job execution. Try increasing the timeout window in the SIP trunk settings to absorb the initial spike without dropping connections.

The simplest way to resolve this is to decouple the WFM notification trigger from the SIP trunk session logic via Terraform. Increasing max_concurrent_sessions is a temporary patch that risks hitting provider hard limits. Instead, configure the WFM schedule to use internal routing for availability checks. This prevents the burst from hitting the external trunk entirely. Use the genesyscloud_wfm_schedule resource to set notification_method to internal.

resource "genesyscloud_wfm_schedule" "main" {
 name = "Agent Schedule"
 notification_method = "internal" # Avoids SIP trunk
}

Deploy this change before the next Monday cycle. Monitor the genesyscloud_sip_trunk metrics for session drops. The internal method uses platform queues, not SIP sessions. This removes the timeout errors at the source. Do not rely on timeout increases alone. The platform documentation notes that internal notifications are more reliable for bulk updates. Check your deployment logs for any validation errors during the apply phase.