單項(xiàng)選擇題

通過(guò)Um接口監(jiān)測(cè)儀表觀察,可能觀察到的GPRS ATTACH信令流先后順序是()

A.ATTCHREQUEST-SECURITYFUNCTION-ATTCHACCEPT-ATTCHCOMPLETE 
B.ATTACHREQUEST-SECURITYFUNCTION-ATTACHCOMPLETE-ATTACHACCEPT 
C.ATTACHREQUEST-ATTACHACCEPT-SECURITYFUNCTION-ATTACHCOMPLETE 
D.SECURITYFUNCTION-ATTACHREQUEST-ATTACHACCEPT-ATTACH

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