KUALA LUMPUR, March 15 — Establishing signals such as those from missing Malaysia Airlines flight MH370 are sent when satellite communications equipment onboard is functional but not being used, according to London-based firm Inmarsat.

Responding to queries by UK’s The Guardian on the revelation that it received a series of “pings” each an hour apart from the Beijing-bound flight now missing for over a week, Inmarsat vice president of aviation David Coiley said there were the plane’s “acknowledgement” of the communications network.

“When the system is not transmitting or receiving data on the aircraft, it will send network signalling info to establish that the aircraft satellite communication is switched on, to say that the system could communicate,” Coiley told the newspaper’s transport correspondent Gwyn Topham.

But Coiley was quick to say that the pings by themselves did not convey anything other than the plane’s equipment were functional but silent.

When asked by Topham if such a scenario would gel with investigators’ hypothesis that the plane’s two transponders were turned off, Coiley replied in the affirmative.

The Inmarsat system is found on nine in 10 commercial airliners that ply long-distance routes.

Yesterday, the firm revealed that it continued to receive the establishing signal from the Boeing 777-200ER that was carrying 239 onboard when it vanished a week ago.

Investigators are now increasingly entertaining the possibility of some form of foul play in the mysterious disappearance.

The latest revelations has also led search and rescue efforts to expand further, and now included the Indian Ocean where the plane would have had enough fuel to reach.