To ensure more passengers get a ticket, the 12306.cn online booking site is restricting the number of “unverified” travellers on booking accounts.
The Summer Peak Travel Season will last from 01 July 2015 through to 31 August 2015. To enable all passengers to get tickets for travel, China Railways is adjusting its online booking policy for the two months.
During this time, an account on the official online booking site, 12306.cn, may only buy tickets for a maximum of 30 passengers who have not completed the obligatory ID Verification at stations. This will, however, not affect you if you presently have more than 30 such passengers in your online contact list. It will also not affect those who have passed ID Verification inspection at stations. This also does not affect “regular” phonebooking, or ticket purchases at stations or ticket machines.
To complete ID Verification procedures, please take your passport (or other ID you have used at booking) and either your ticket, or provide your order number (which should start with “E”), to the dedicated ID Verification (网购身份核验) counter. This might take you a while, especially if you present a foreign passport, since they will need to check if you are, well, “yourself”. However, once this is completed, you will be “approved”, although for passport holders, this can take a while even after leaving the counter.
This is to ensure only legitimate travellers are assured their ticket over the holidays.