An interesting thing I noticed was that all cell phones were completely useless for a pretty long time following the quake. That's normal, but one difference this time, compared with several years ago, is that most people I know no longer have a landline phone at home. People were queuing up for like 20 minutes to use the one old green plastic coin-op pay phone accross the street.
At first, I didn't think to use a phone, since I was sitting at my desk and email worked normally. I could email a colleague in a different building back and forth in neartime while the quakes were happening. About 15 minutes later it occurred to me to try my (naz)iPhone and see if it was useful. It was not--could not make or receive calls, and the test text message I sent did not arrive in a timely manner (took more than 30 minutes).
I experienced this after the Christchurch earthquake. Without electricity cordless phones are also useless. Our national communications company put a message out asking everyone to bring in their old corded phones so they could be sent down to Christchurch.
Smartphones were better than regular phones during this emergency. My android phone was useless for voice and SMS, but still had a data connection. So, my wife and I were able to send gmail back and forth to stay in touch.
Also, the landline data networks seemed to be up and stable, so Skype worked great. Something to remember next time you're in an emergency and need to get a call out.
I strongly suspect this is not due to an outage in the network, but rather intentional. Some years ago I worked on a project for a Japanese mobile operator to implement a system that prevents "normal" mobile phones from making calls to avoid overloading the network. When activated, only emergency services (fire fighters, police, medical, ...) are allowed to call. At regular intervals, a batch of the "civilian" phones are allowed too for a while, then a different batch, etc, so everyone gets its chance to call if they wait long enough.
The system was a government requirement for events such as yesterday's quake, but I can't confirm all phone disturbances reported were/are due to it.
Technically, it relies on a bitpattern called "accessClasssNBarred".
Isn't that strange ? I mean cable should be more easily broken than airwaves, no ? Is it because the landlines in Japan are designed to resist and the cell phone tower got power disruption ?
It's because everyone in Japan started sending SMSes to everyone they knew practically before the shaking stopped and that DOSed the network. This happens fairly regularly (e.g. for a few minutes after midnight on New Years, when a large portion of Japanese people send well wishes within the same 15 second window).
Landline phones (pre-ISDN) can get their power from the network, thus mitigating one failure vector.
Also, it is much cheaper to provide enough cable than radio transceivers. Thus mobile networks nearly always run close to full capacity... ever had "network busy" on your phone when dialing in a downtown? So they are easily overwhelmed in emergencies. With landline, in contrast, you always have the line, so it is mostly a matter of installing big enough BX station.
stay with it. The telcos in New Zealand got COWS (mobile cell sites) and new cell sites/equipment down to Christchurch very quickly - importing some from China (Huawei gear I guess). Landlines take much longer to repair, and cells have redundancy - can link together with fibre or microwaves.
At first, I didn't think to use a phone, since I was sitting at my desk and email worked normally. I could email a colleague in a different building back and forth in neartime while the quakes were happening. About 15 minutes later it occurred to me to try my (naz)iPhone and see if it was useful. It was not--could not make or receive calls, and the test text message I sent did not arrive in a timely manner (took more than 30 minutes).
Just as a data point.