Introduction GSM Hosted SMS Teleservice@ GHOST@ is used to deliver GSM SMS Protocol Data 4 Units (PDUs) to and from a mobile station operating in a TIA/EIA-136 network. The 5 Higher Layer Protocol Data Unit field in the R-DATA Unit information element is used 6 to carry the GSM SMS PDUs when the Higher Layer Protocol Identifier indicates 7 GHOST. Refer to GSM 03.40 and GSM 04.11 for a full description of the GSM SMS 8 PDUs. It should be noted that network support for GHOST operation is beyond the scope of this 11 document and references to the Message Center are only provided to aid in describing the 12 support of GHOST operation over the air interface.