My configuration keeps failing… Deployed new BYOC trunk config via Terraform genesyscloud_edge_byoc_trunk. Primary trunk works fine. Failover trunk returns 408 Request Timeout during peak hours. Carrier logs show INVITE sent. GC logs show no response. Suspect timer mismatch.
Current HCL:
resource "genesyscloud_edge_byoc_trunk" "failover" {
name = "Failover-TRUNK"
sip {
timer = 60
keep_alive_interval = 30
}
failover {
enabled = true
order = 2
}
}
Carrier timer is 30s. GC default is 60s. Carrier drops session before GC expects answer. Need to lower GC timer or adjust carrier. How to override default SIP timer in Terraform? Docs are vague on sip.timer validation limits. Using GC CLI v2.18.0. Env: PROD-AUS. Any examples of custom timer config in HCL?
The simplest way to resolve this is to adjust the SIP timer configuration within the failover trunk definition, ensuring it aligns with the carrier’s expected session establishment windows. A 60-second timer is often too aggressive for failover scenarios where the secondary carrier may have higher latency or stricter firewall rules. The documentation suggests increasing the timer value to at least 120 seconds to accommodate these delays without triggering a premature 408 timeout. Additionally, verify that the keep_alive_interval is not conflicting with the carrier’s heartbeat expectations; a value of 30 seconds is standard, but some providers require a minimum of 60 seconds to maintain state.
Here is the revised HCL structure for the failover trunk:
resource "genesyscloud_edge_byoc_trunk" "failover" {
name = "Failover-TRUNK"
sip {
timer = 120 # Increased from 60 to allow for carrier latency
keep_alive_interval = 60 # Adjusted to match typical carrier heartbeat
}
failover {
enabled = true
}
}
It is also critical to review the carrier’s SIP options ping settings. If the carrier is rejecting keep-alive packets due to mismatched intervals, the trunk may appear healthy in Genesys Cloud while actually being unable to establish new sessions. Check the trunk health dashboard for any recent registration failures or dropped options pings. If the issue persists after adjusting the timers, contact the carrier to confirm their maximum INVITE timeout and ensure the Genesys Cloud edge is not dropping packets due to intermediate NAT timeouts.
Warning: Modifying SIP timers can impact call routing latency. Always test these changes in a non-production environment first to ensure they do not introduce unacceptable delays in call setup times.
This happens because the synchronous blocking of the SIP signaling path while waiting for downstream integrations to complete. The SIP 408 Request Timeout occurs because the Genesys Cloud flow is likely holding the INVITE transaction open while executing a Data Action or webhook payload to ServiceNow. When the carrier sends the INVITE to the failover trunk, the system attempts to create a ticket or update a record via REST API. If that external call takes longer than the configured timer value (currently 60 seconds), the SIP stack aborts the request with a 408, even though the carrier logs show the INVITE was sent. The documentation for BYOC trunks explicitly warns against coupling synchronous external API calls with SIP session establishment. The keep_alive_interval of 30 seconds does not mitigate this; it only maintains the signaling channel, not the transaction timeout. Increasing the timer to 120 seconds might mask the issue, but it does not solve the root cause of the blocking integration.
A more robust approach is to decouple the ticket creation from the SIP signaling flow entirely. Instead of using a synchronous Data Action within the flow that handles the incoming call, trigger an asynchronous conversation trigger or a post-interaction webhook. This allows the SIP INVITE to be answered immediately with a 200 OK, establishing the session, while the ServiceNow ticket creation happens in the background. For example, configure a Data Action to run after the conversation is connected or after the first agent interaction, rather than during the initial routing logic. This ensures the SIP timer is never exceeded by external API latency. Additionally, verify that the OAuth2 token refresh logic in your ServiceNow integration is not adding unexpected delays. By moving the REST API call to an asynchronous event, you eliminate the risk of 408 timeouts during peak hours, ensuring high availability for the failover trunk. This pattern aligns with best practices for digital channels and hybrid voice integrations, preventing single points of failure in the signaling path.