Trying to understand why our Genesys Cloud SIP trunk registration is consistently failing with a 403 Forbidden error when connecting to our ServiceNow-integrated PBX gateway, despite the username and password matching exactly what is configured in the ServiceNow CMDB and verified via direct SIP ping. The Architect flow is triggered by the conversation_start event on the digital channel, which then attempts to route to this SIP endpoint, but the registration handshake fails before any media is established, and the Genesys Cloud logs show no specific error code other than the generic 403 from the upstream provider. We have confirmed that the IP address is whitelisted in both the Genesys Cloud SIP settings and the ServiceNow firewall rules, and the SIP URI format matches the documentation for version 2023-11, but the issue persists across multiple test agents in the London timezone. Has anyone encountered a scenario where the SIP registration fails with a 403 even when the credentials are correct, and what specific headers or authentication methods should be checked in the Genesys Cloud SIP trunk configuration to resolve this?