Having some issues getting my configuration to work… We are deploying a new AppFoundry integration that requires direct SIP trunking capabilities via a partner-hosted Session Border Controller. The environment is a Genesys Cloud US-2 tenant, and we are utilizing the standard multi-org OAuth flow for the initial API handshake, but the SIP registration phase is failing consistently. The SBC is configured with the correct tenant domain example.genesiscloud.com, and the credentials match the user profile created specifically for this integration. However, upon attempting to register, the SBC logs show a 403 Forbidden response from the Genesys Cloud edge, with the specific error message SIP_REG_AUTH_FAILED_INVALID_TOKEN. We have verified that the user account has the TelephonyUser and SipTrunkManager roles assigned, and the network connectivity between the SBC and the Genesys Cloud endpoints is open on ports 5060 and 5061 via TLS. The issue appears to be related to the token validation process during the SIP REGISTER request, where the platform seems to reject the authorization header despite the OAuth access token being valid for other REST API calls. We are using the latest version of the SBC firmware, and the integration code is written in Node.js, handling the token refresh logic automatically. The problem persists even after rotating the credentials and recreating the user profile. There are no rate limiting errors in the platform logs, which suggests this is not a throttling issue. The integration is designed to handle high-volume inbound traffic, so reliability is critical. We need to understand if there is a specific configuration requirement for the SIP trunk authentication that differs from standard OAuth flows, or if there is a known limitation with custom tenant domains in the US-2 region. Any insights into the specific validation steps Genesys Cloud performs on the SIP REGISTER request would be appreciated, as the documentation does not explicitly detail the token structure expected in the SIP headers for partner-hosted SBCs.