Mifis are mobile wireless routers which act as a mobile WIFI hotspot. Thus different mobile devices can be linked via WIFI and the Mifi with the internet. In some countries it is a registered brandmark, in most countries of the world, it is used as a synomym for portable routers to act as an hotspot.
The devices are often pocketsize and smaller than a smartphone. One disadvantage of Mifis is their limited battery power supply which often lasts only up to few hours before it needs to be recharged. Only with an additional battery or "power bank" you reach running periods compared to smartphones.One big advantage is that often up to 10 different mobile devices can all linked at one time to one common internet access. But the same can be done without using Mifis by using Tethering too.
MIFIs in this WIKI Edit
In some countries where it can be tricky or expensive to buy a local SIM card, MIFI rental agencies are listed in this WIKI like Turkey, France, Korea or Japan. They supplement the national offer and can be suitable for users who have problems in purchasing a local SIM card. Mifis overcome technical system barriers like CDMA-networks or legal hurdles like registration issues when they operate on a local SIM card provided by the Mifi rental company.
MIFI rental Edit
Some MIFI rental agencies have discovered this WIKI as a tool for advertisement. While phone network providers are presented in an unbiased way, they praise their MIFI with all the ad talk you can imagine. These offers need to be revised constantly not to cheat. So better check twice, if you are interested in a rental.
Generally, you have the device sent by mail or courier to a local address. Be sure that this is registered and included in the rate. You need to have a place of which you are pretty sure of, that they pass on your delivery to you. After the rental term, you need to return the device again to the agency by mail. Again, be sure, it's certified. Whether the whole procedure is so easygoing as it's promised, it's up to you to decide.
The problem with MIFI rental is, that you have the full liability for the device all the time, even when it's outside of your reach. This refers to the transport to you and back and all damages which may occur during your rental and you may or may not be responsible for and of course for its loss too. None of the offers listed provide you an insurance for the device at extra cost. As they bill your credit card, they can charge you all over the world. If they accept special payment systems like PayPal, they often require a deposit.
So it should be pointed out that MIFI rental implies a certain risk which is solely on the side of the renter. This is often hidden in their T&Cs you have to agree to or sign. Another alternative can be the purchase of the device as offered by one company in the international section.