looking for advice on sip trunk registration failing after we moved our zendesk voice channels to genesys cloud. the trunk shows as registered in zendesk but in genesys cloud architect flow it keeps dropping with a 408 request timeout. we are using the standard sip trunk connector and the logs show a 503 service unavailable from the upstream provider. in zendesk this was handled by the sidekiq workers but here it seems synchronous. the flow is simple: inbound call → answer → transfer to queue. but the transfer fails with error code 487 request terminated. we checked the firewall rules and ports 5060 and 5061 are open. the timezone is europe/paris so maybe there is a scheduling conflict with the wfm integration? not sure. the contact attributes are mapping correctly from the zendesk ticket fields but the voice part is broken. any ideas on how to debug the sip invite sequence? we are using the latest version of the genesys cloud platform. the error log shows a malformed sip header but we are using the default templates. please help.