The Inmarsat Communication Log provides the following details:-
18:39 - Ground Initiated to Air Telephony Call - Zero Duration (Not Answered)
18:39:52.907 | IOR-P10500-0-386B | IOR | 301 [BURUM NL] | 10 | P-Channel TX | 0x20 - Access Request/ Call Announcement Telephone/ Circuit-Mode Data
18:39:52.907 | IOR-P10500-0-386B | IOR | 301 [BURUM NL] | 10 | P-Channel TX | 0x33 - C-Channel Assignment (Regularity)
18:39:55.354 | IOR-3730-21000 .... | IOR | 305 [PERTH AU] | 06 | C-Channel RX | 0x30 - Call Progress - Test | 88 [BFO]
18:40:56.354 | IOR-3730-21000 .... | IOR | 305 [PERTH AU] | 06 | C-Channel RX | 0x30 - Call Progress - Channel Release | 90 [BFO]
Remarks in [brackets] added by me, and a duplication of the BURUM data in the log is not reproduced here.
The unanswered call was routed via BURUM in the Netherlands. While the most relevant thing is that PERTH checked the call progress and subsequent release, which resulted in two BFO's.