3.2.5.3.7 Receiving an SSTP_MSG_ECHO_REQUEST Message
If CurrentState is set to Client_Call_Connected:
Restart the Hello timer (section 3.1.2.3).
Send an SSTP_MSG_ECHO_RESPONSE (section 2.2.15) message.
Else if CurrentState is set to Call_Abort_Timeout_Pending, Call_Abort_Pending, Call_Disconnect_Ack_Pending, or Call_Disconnect_Timeout_Pending:
Ignore the message.
Else if CurrentState has any other value:
Change CurrentState to Call_Abort_In_Progress_1.
Send an SSTP_MSG_CALL_ABORT (section 2.2.13) message.
Start the TIMER_VAL_ABORT_STATE_TIMER_1 timer (section 3.1.2.1).
Change CurrentState to Call_Abort_Pending.