HSS-link is down and SMS MT in VoLTE network for Home Routed non-Ultracard Traffic (Incoming messages via MTI-Rule) from foreign networks is not being delivered.
Non-ultracard messages are being rejected with temporary error and no SMS delivery for foreign network customers in the VoLTE network is possible.
This was determined to be an RTR bug that was addressed through RTR R04.12.10.06 hotfix which is now available to address this issue.
See attached ZephyrTel RTR-R04.12.10.06 Release Notes V01.00 for confirmation.
The fix is now present in version 18.10.99.
Upgrade requests will be escalated to Professional Services Team who will then reach out to the customer for the tests planning.