A Palestinian man walks on debris from a damaged building after it was hit by an Israeli airstrike in Beit Lahiya, northern Gaza Strip, on Tuesday. (Adel Hana/Associated Press)

On Wednesday night, the Israeli newspaper Haaretz reported that the Israel Defense Forces was using recorded telephone messages to warn more than 100,000 residents in two Gaza City neighborhoods to evacuate their homes. Given that the Gaza Strip contains just 1.7 million people total, that's a huge number of people.

The blanket warning policy coincides with a more precise tactic. Before the IDF targets a home, it often calls the occupants. "Get out. You have five minutes before the rockets come," is how one Gaza resident described her phone call to The Post. These warnings are often followed by a "roof knock" — a small missile to let the occupants know the Israelis are serious.

The use of telecommunications to warn civilians appears to be a legitimate attempt to limit the loss of life in a conflict in which Palestinians remain far, far more likely to die than Israelis, and the IDF is very open about the practice, releasing videos of the practice in action. Scratch the surface, however, and these warning phone calls also reveal something else — the remarkable ability of Israeli authorities to penetrate the communications of Palestinians.

How could the IDF so easily access telecommunications in the Gaza Strip, knowing exactly whom to call at each residence? It's incredibly simple. While the telecommunication companies that operate in Gaza, such as the Palestinian Telecommunication Group (PalTel), are owned and operated by Palestinians, they are routed through servers based in Israel. These servers are easy for Israel's intelligence community to access and can provide an important resource for the IDF.

This setup goes back to the Oslo Accords almost 20 years, to when Israel recognized "the right of the Palestinian side to establish telecommunications links (microwave and physical) to connect the West Bank and the Gaza Strip through Israel" (in Article 36 of Oslo II, 1995). At the time, this was viewed optimistically by those in the West Bank and the Gaza Strip. While some Israeli-administered telecommunications structures existed in the Palestinian territories, few Palestinians actually had access: Just 3 percent of Palestinians had land phones in 1996, according to a Christian Science Monitor article from the time.

However, the creation of PalTel and the Palestinian telecommunications industry faced an unusual problem: Much of the infrastructure it was using remained linked to Israel. For example, the Palestinian territories didn't have their own international gateway, and even now, when the Palestinian territories have their own international dialing code, all international calls and the vast majority of domestic calls require routing through Israel. Palestinian Internet service providers are effected, too, having to buy bandwidth from Israeli providers.

Critics say that Israel exploits the Oslo Accords by refusing to allow Palestinian companies to buy the equipment that would grant it independence from the Israeli networks. The way the system is set up now allows Israeli intelligence easy access to Palestinian telecommunications, Michael Dahan, an Israeli American political scientist and technology researcher at Sapir College, says.

"The ability to take over (command and control) the networks was either embedded in the systems prior to Palestinian control, and/or achieved via Unit 8200 (a miniature version of the NSA), a signals intelligent unit of the IDF," Dahan writes in an e-mail. In the past, the IDF has been accused of shutting down the Internet at times of conflict or using cellphone signals to target Hamas members. And Dahan argues that Israel's reach over Palestinian telecommunication has even wider consequences, helping to "advance a form of psychological warfare – 'we know who you are, we can reach you anywhere.'"

Of course, even if Israel's telecommunications system was not intertwined with that of the Palestinian territories, it would probably be able to access much of this anyway: The Israeli intelligence community is hardly known as Luddites. If it can hack Iran, as it is so often said to be able to, hacking into the Gaza Strip shouldn't be too difficult. But Sam Bahour, a Palestinian American business consultant based in Ramallah who immigrated to the West Bank to help set up PalTel in 1994, tells me, that isn't really the point. Bahour argues that, for all the talk of a "tech boom" in Palestinian territories, Israel's grip on the telecommunications industry is so strong that Palestinian cell networks can't even provide 3G networks, let alone 4G.

"All of our smartphones in Palestine are dumbphones," Bahour says.

More infuriating still, he says, is that many Palestinians end up buying SIM cards for the Israeli networks that operate in the Gaza Strip in a bid to get a better technological service, despite this being restricted by the Oslo Accords. In 2012, the World Bank estimated that this practice was costing the Palestinian Authority $100 million a year, and a report from the Office of the Quartet Representative Tony Blair this year estimated that Israeli operators got a share of 20 to 40 percent of the Palestinian telecommunications market.

It's worth keeping these points in mind when you hear the reports of the thousands of phone calls being made to Gaza civilians. Those calls can be thought of as humanitarian warnings – but many on the other end may well view them as a reminder of how powerless they are.