Here is some background on communication systems used by MH370, collated from various sources - please drop me an email to correct the details.
ACARS is Aircraft Communications Addressing and Reporting System. ACARS rely on VHF frequencies or SATCOM (SATellite COMmunication).
Quoting from http://theaviationist.com/2014/03/16/satcom-acars-explained/
"SATCOM is a radio system that uses a constellation of satellites used to trasmit voice, data or both. As said, ACARS can make use of SATCOM to transmit its data to ground stations. Dealing with ACARS, the SATCOM system used by MH370 was linked to the INMARSAT network."
Quoting from http://www.duncansteel.com/archives/701#comment-2603 (comments from Don):
"The engine health monitoring and all other packet messaging will use the same data path: ACARS", and also "All the aircraft data services use the ACARS protocol messaging to SITA’s hub over VHF or SATCOM. In MH 370′s case they chose to select satcom only."
GES is Inmarsat's Gateway Earth Station (aka "ground station").
AES is Airborne Earth Station (deployed on a plane). AES does not ping hourly. It is supposed to respond to the pings from GES, as well as send some registration messages, e.g. it can register the plane's unique identifier.
Quoting from http://tmfassociates.com/blog/2014/03/
"The ‘ping’ is a component of the Aero-L [or Aero-H] protocol where the GES [Inmarsat's Gateway Earth Station] attempts to check the ‘log-on’ state of previously logged on but apparently idle AES [the plane's Airborne Earth Station]. The GES determines the AES to be idle if a timer ‘tG6′ expires, tG6 is obviously the hourly period. The GES transmits to the AES over the P channel & receives over the R channel. "
Continuing from http://theaviationist.com/2014/03/16/satcom-acars-explained/
"...the ACARS transmissions can be switched off by the pilot from inside the cockpit, by disabling the use of VHF and SATCOM channels."
However, apparently, the AES responds "even if the SATCOM is not being used by any onboard systems (i.e. ACARS)." Let us call this an "embedded feature" of AES, as it does not rely on SATCOM.
Also, according to AAIB: http://theaviationist.com/2014/03/27/inmarsat-helps-finding-route/
“If the ground station has not heard from an aircraft for an hour it will transmit a ‘log on / log off’ message, sometimes referred to as a ‘ping’, using the aircraft’s unique identifier. If the aircraft receives its unique identifier it returns a short message indicating that it is still logged on. ”
Now let's consider the following question. The ground station was supposed to send a ping at 7:40 (23:40 UTC), as it did at 6:40, 5:40, etc. If it didn’t do it, but sent another ping at 8:11 (00:11 UTC), it may mean that the plane communicated something itself at 7:11 (23:11 UTC). This time can be marked precisely because of the 8:11 ping, which must have followed an hour of silence – according to the AAIB protocol, quoted above.
So what could have been an undisclosed communication at 7:11 (23:11 UTC)?
If it was a ping initiated by the plane (via the embedded feature of AES) and sent to the ground station, like the incomplete attempt at 8:19, then AAIB would have released this event with the rest of "handshakes".
Another scenario seems more possible: SATCOM channel used by ACARS was activated briefly around 7:11, some downlink signal was sent via SATCOM, and then it was switched off. Having registered this event, GES, the Inmarsat ground station, did not need to ping at 7:40, since an hour has not yet passed by then. It did, however, need to ping at 8:11, after one hour.
That is, in order to explain the gap around 7:40 (23:40 UTC), one needs to hypothesize that something triggered a new hourly "cycle" at 7:11 (23:11 UTC) - quite likely, a downlink message 7:11 via a SATCOM channel used by ACARS. Perhaps, it means that someone switched the channel(s) on temporarily, for a brief communication with some party on the ground.