Plain-language definition
A message sent from a handset.
Technical definition
MO SMS travels from the UE to the serving MSC/VLR (or IMS core), which forwards it to the SMSC with MAP MO-ForwardSM (or SIP MESSAGE). The SMSC then handles onward delivery.
Why it matters
MO handling is where SIM-box traffic enters the network and where firewalls must inspect subscriber-originated commercial patterns.
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.