Systems and methods provide solutions for reliable data transfer in a mobile communication network. A user equipment (UE) may indicate to the mobile communication network a capability of the UE to support a reliable data service protocol. The UE may process non-access stratum (NAS) messages, for both mobile originated (MO) data transfer and mobile terminated (MT) data transfer, using the reliable data service protocol to determine whether protocol data units (PDUs) of the NAS messages require no acknowledgement, require acknowledgment, or include an acknowledgement, and to detect and eliminate duplicate PDUs received at the UE in the NAS messages.