Plain-language definition
The HLR telling the SMSC that a subscriber is back.
Technical definition
MAP AlertServiceCentre is sent by the HLR to SMSCs listed in the subscriber's MWD when the subscriber becomes reachable, triggering immediate retry.
Why it matters
AlertSC minimises delivery delay for stored messages.
Last reviewed 2026-09-12 by the Guardivia QoS Engineering Team. Product facts on this page describe current capabilities; items marked “where supported”, “optional”, “integration” or “consultancy” are confirmed per deployment.