Purposefully block your cell phone signals.
比如说，现在是你的大学考试季节，你想不受干扰地学习一段时间，或者，你的亲戚时不时打电话来烦你，或者，you don't want to talk to anyone but at the same time you don't want to hurt someone's feelings by hanging up in the face or by rejecting their calls or,maybe your girlfriend wouldn't stop calling you...不管是什么情况，It could be pretty hard to ignore calls and come up with some legitimate reason at the same time.但在这之后…
The most forgivable Excuse for not picking (or not receiving any calls in the first place) calls is definitely a USER NOT REACHABLE or an OUT OF COVERAGE message from the service provider.如果你不在保险范围内，为什么会有人争论？？But in this connected world,one can only be out of coverage if he is living underground or something...Well,In this instructable,我将向你们展示如何创建自己的个人和便携式的不可到达区域。麦克尔·法拉第支持你。
Also,this project will help you understand why your phone loses signal in a closed type elevator.
Step 1: A Little Bit of Science and History About Faraday Shield/cage
A Faraday cage operates because an external electrical field causes the electric charges within the cage's conducting material to be distributed such that they cancel the field's effect in the cage's interior.This phenomenon is used to protect sensitive electronic equipment from external radio frequency interference (RFI).Faraday cages are also used to enclose devices that produce RFI,such as radio transmitters,防止他们的无线电波干扰附近的其他设备。它们还用于保护人员和设备免受雷击和静电放电（或玩高压特斯拉线圈的疯子）等实际电流的影响，因为封闭笼在封闭空间的外部传导电流，而没有电流通过内部。
Step 2: Gather All the Components
This little project can easily be made using some household junk.
- Sneak into your girlfriend's/sister's room and find the box of her most expensive shoes.Throw away the shoes because you won't be needing them and keep the box,that's what you'll be needing.这是你自己的风险！…你需要找到一个相当完整的鞋盒或任何纸板箱的大小大致相同。
- aluminum foil
- A shielded cable.It's not absolutely necessary to use shielded cable,you can use solid copper wire too but shielded cable worked best for me.通常，优质的USB电缆被屏蔽，在电缆盒中找到一个备用电缆（每个房间至少有一盒电缆：P），然后切断两端的USB连接器，剥开外部绝缘层，你会看到内部电线周围有一个金属丝网（金属丝网的用途类似）。It acts as a Faraday cage and prevents any exterior electrical interference while transferring data).
- access to mains earth connection（在电源周围工作时要非常小心，根据当地标准电气连接规则，确保哪个连接是接地的。In India green wire is the earth connection red is Hot i.e.220VAC和黑色为中性。Also,make sure the switch is in off position because the project does not require any power only earth connection is needed for which you don't have to turn on the power switch as it is directly connected to ground.If you absolutely have no idea on how to work with mains then,stay away or ask an adult or experienced personnel for help)
- and last but not the least A roll of Electrical tape.
Step 3: Okay Let's Build It
- 开始在盒子的外表面贴铝箔。Try keeping the foil in as one single piece as possible.if any tears or gaps arrises,use some more aluminum foil as a patch on the torn areas.make sure all of the outer faces are wrapped in a single piece of aluminum foil.关闭盖子时，所有表面必须具有良好的电气连接。
- Strip off the outer insulation of shielded USB cable and twist the outer mesh as shown.you snip inner wires or you can strip them off twist them together along with the mesh wire.
- Use stapler pins to connect the wire to the aluminum foil on any of the exterior faces of the foil covered box.make sure it makes a good electrical connection.
- Strip the insulation off of the free end of the wire and twist the wires as before.
- 将自由端连接到地/地connection of the mains power socket.( I taped the free end of the wire to the metallic shaft of a screwdriver because I couldn't find anything else to insert in the plug and the wire alone was just too flimsy it kept falling off the earth/ground connection.) AGAINBE CAREFUL WHILE WORKING WITH MAINS SOCKET.如果你不知道它是如何工作的，不要尝试它。ASK AN ADULT OR EXPERIENCED PERSONNEL FOR HELP.MAKE SURE THE POWER SWITCH IS ALWAYS OFF.
- 把你的手机放在盒子里，合上盖子，试着打那个电话。如果所有的东西都连接好了，箔纸上没有空隙，then you'll hear an "UNREACHABLE" message.
There you have your very own out of coverage area or Faraday cage.现在你可以不理别人的电话了。
SO,商场内的封闭式电梯类似于铝箔包装箱，they too are connected to earth which makes them a FARADAY CAGE and due to this Faraday cage effect,你的电话在电梯里失去信号。
Step 4: YAY...它的工作原理……
the OUT OF REACH message might vary for different service providers.在我的案例中（bsnl）消息指出，“你试图联系的人要么被关闭，要么被移出覆盖区域”
also when you put your phone on flight mode,您的网络报告您的号码已关闭。
免责声明：This project is meant for educational and informational purposes only and I'll not be responsible for any damages.