The telephone number is the number set by the telephone management department for the telephone. Generally, it consists of 7-8 digits (mobile phone number is 1 1 digit), with 5-6 digits in the early stage.

The designated number set by enterprises, organizations, factories, mines and institutions for internal communication such as fixed telephones or mobile phones is generally 4-8 digits in length. It is also equivalent to the number and name of each mobile phone.

The capacity problem of section number.

Domestic mobile phone numbers are uniformly planned by the Ministry of Information Industry. Originally, it was 10 bit, but due to the continuous growth of users, the number of 10 bit was not enough, so it was upgraded to 1 1 bit. The format of mobile phone number is 1 1 digit in China, which is the longest telephone number in the world. Why 1 1 digit? There is a simple reason.

Because a number combination of 1 1 has hundreds of billions of numbers. And even if the first two digits of "13" are removed, there are 9 digits left, and the number of combinations of 9 digits ranges from 130000000 to 13999999, which can accommodate1000 billion different numbers. How many people are there in China? The telephone penetration rate of 1 100 million people has not reached 100%, so it is simply not enough.

Even if the future penetration rate reaches 100% or one person has two telephones, if we fix the number "1" in the first place, the capacity of the second place will increase by 100 billion.