What's the number of121?

"12 12 1" is an automatic weather forecast consulting service. Telecom customers can dial "12 12 1" on any fixed telephone or PHS to connect to the weather forecast computer automatic service system of the Meteorological Observatory. The service content includes conventional weather forecast information and unconventional weather forecast information (also called professional meteorological information). Urban short-term weather forecast (24: 00 or 36: 00) is a routine weather forecast, also known as public weather forecast, which is often released to the public through TV stations, newspapers and other media. Unconventional weather forecast information includes: medium-term weather forecast (more than 48 hours, including 3-5 days, holidays, ten-day weather trends, etc. ), weather reality, disastrous weather trends, meteorological index forecast, various meteorological astronomical knowledge, meteorology and human health, knowledge related to people's work and life, etc.