(Chinese Version)

On March 18th, Mark Zuckerberg posted a photo on his Facebook timeline, in which he was running across the Tiananmen square. It is worth noticing that he added “Tiananmen Square” as the location.

You might wonder: which VPN did he use to climb over the GFW?

As a matter of fact, however, Zuckerberg got access to Facebook via the international roaming service.

That’s why you would only see 404 when getting access to Facebook.

Following, let me introduce to you briefly how the international roaming service work?

First of all, I’d like to talk about international roaming service for voice calls, in other words, making phone calls abroad via the international roaming service.

Suppose you are just arriving at San Francisco, Hokkaido or London… No matter where you are going, what’s the first thing you need to do after you get off the plane?

Yep, going through the Customs. You will be allowed entry only when Customs officer confirm your identity and make sure that you are a good guy.

This rule also applies for your smartphones.

When you are going through the Customs, your smartphones will also need to “go through the Customs”, not a real one, but at the local network.

However, you don’t need to do anything, since your smartphones will automatically do that.

The following is the basic procedure (take the example of a user of China Mobile):

Step One: For users who enjoyed the international roaming service, your smartphone will automatically send a request to local network to update the location after you arrived at a place abroad. You don’t have to do anything, but your smartphones will have already said “Hello” to the local mobile carriers.

Step Two: The local mobile carrier will turn to China Mobile to see if you are a good guy or not? Just kidding, the local mobile carrier actually asks China Mobile if you are a credible user of China Mobile? If so, China Mobile will grant you five “cards”, with which you can make phone calls abroad, just like every other local user.

Step Three: You can only make phone calls for a designated period of time with each “card”, so you will have to use another “card” if you’ve already used up the phone call time of the former “card”. When you are going to use up all the five “cards”, you will be granted another five “cards” when the system automatically sends a request and confirm that your account is still valid. However, if the system finds out that your account is out of credit and shut down, you will not be granted with “cards” anymore, and you couldn’t make any phone calls anymore abroad.

Step Four: Only when local mobile carriers send your bill back to China Mobile can it know how many phone calls you have made, who you have called, and how long you have called somebody.

However, things would be a little bit different when you surf the Internet abroad via the international roaming service.

The following is the basic procedure (take the example of a user of China Mobile):

The first two steps are the same as voice calls’: your smartphone also needs to update the location and the local network will have to confirm your identity before allowed “entry”.

Different from voice calls, you are not granted special “cards” to surf the Internet abroad. Instead, your request will be sent back to China Mobile every time you try to surf the Internet. After China Mobile confirmed that your account is credible, you will get access to the Internet via China Mobile’s network.

In other words, your requests to surf the Internet will be directly sent back to China Mobile. If your account is still valid, then China Mobile will allow you to get access to its network abroad.

Thus, no matter when you are, you will have to get access to the Internet via China Mobile.

Scenario One: Chinese users of China Mobile’s international roaming service will have to get access to the Internet via the Chinese GGSN and be restricted by the GFW when surfing the Internet abroad.

Scenario Two: Foreign users of international roaming service will have to get access to the Internet via the foreign GGSN when visiting China.

This may help explain why Zuckerberg can get access to Facebook at Tiananmen Square, and why we couldn’t use Google Map even when we are abroad.

However, if Chinese users get access to the Internet not via China Mobile’s international roaming service, but via the local WIFI signal, then they will be able to surf the Internet via the local network.

Therefore, I highly advise you to have a local SIM card or a portable WIFI gadget with you so as not to get lost abroad.

At last, I believe Zuckerberg won’t be able to climb over the GFW when he comes back to his hotel and connects to the WIFI at the hotel.

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[The article is published and edited with authorization from the author @Ning Yu, please note source and hyperlink when reproduce.]

Translated by Levin Feng (Senior Translator at PAGE TO PAGE), working for TMTpost.