Chongqing

• Chongqing was part of Sichuan and it had the 811 city code until
  8 March 1997. In April 1997, Chongqing became the fourth
  municipality under the direct jurisdiction of the central
  government.
  
• All counties in Chongqing with old 811 code now has the new 23 code.
  
• Chongqin local phone number was changed to 8 digits on March 8, 1997.
  The rules are xxx-xxxx to 6xxx-xxxx for regular numbers, and
  xxx-xxxx to x8xx-xxxx for mobile phone numbers.
  

23	Chongqing
23	Beipei (was 8215, then 811)
23	Fuling (was 810)
23	Jiangjin (was 8221)
23	Nanchuan (was 8291)
23	Wanxian (was 819?)
23	Yongchuan (was 814)
23	Yubei district
23	Banan district
23	Dachuan (was 818)
23	Daxian (was 818)
23	Qianjiang (was 8212)
23	Qijiang (was 8212)
23	Changshou (was 8213)
23	Nantong (was 8216)
23	Shuangqiao (was 8217)
23	Hechuan (was 8222)
23	Tongnan (was 8223)
23	Tongliang (was 8224)
23	Bishan (was 8225)
23	Rongchang (was 8226)
23	Dazu (was 8227)