Brother that picture you have shown is of a TV receiver and not a sat terminal. No sat terminal has a LNB ( low noise block ) these are fitted to tv dishes.
Now a real sat terminal would use a throne and thrane bgan terminal array (you can google it) AGMR1 and 2 have already been decrypted in 2012.
You can gain anonymity using a conventional network by playing around with the invite and 200 OK headers.
This can be achieved by configuring a Cisco 877 type router running on a mpls or OPn / Fftp or even adsl network to treat headers with inv and 200ok and send out masking when sending the 180 early media thus bypassing any attempt to peek when dropping calls at the EX or even LN level.
If you use the old method of listening to the DW/Drop wire at the Dacs this too would not work on a vphones because it is using 802.11n wireless yes you can tap into 802.11n using an am radio but if the caller is daisy chaining and using a unique dial code to connect to a private sip piggybacking on a private assured Cisco router then you would be hard pressed to tap that call. Unless you ran a wireshark type trace on the Lan side and wan side of the SBC handling that call and recorded the .pcap files. Then maybe, trust me that terminal is for TV it has a lnb so it's not a comms terminal