The prefix number is an identification number that makes a call number cheaper when calling a phone number when making a phone call.
Currently, in your mobile phone, you can manually push the identification number in front of the phone number, or in the case of a smartphone, make a phone call using a dedicated application to make a prefix instead of the user.I will give you it.In particular, when using MVNO lines, it seems that it is often provided as a service called "using a dedicated application to reduce call charges" (eg, 30 seconds, 10 yen, etc.).
Typical appointments for this kind of dedicated app include IIJmio's "Miopon Dial", mineo's "MINEO Denwa", and OCN Mobile ONE "OCN Denwa".These are manually replaced the prefix of "0037691", "006751", and "003544".
Conversely, even if you have used a cheap SIM, if you are using a regular smartphone call app, you will have to pay a high price, for example, 20 yen in 30 seconds.I was.
The automatic prefix number is to automatically grant the identification number with the exchange of a business operator.This allows you to obtain the same effect without using the "prefix number" without using the user's hands or smartphone apps.
Speaking of landline phones, if you register the telephone company you want to use in advance, there is a telephone company selection service "My Line" that allows you to make a phone call at the registered company without dialing the company's prefix.It may be similar to this.
However, in the case of a mobile phone, unlike my line, even if you do not do any procedures, you will be selected at the time of selecting a cheap mobile phone company, so it will be easier to choose.It is.
Of the mobile phone companies with equipment such as mobile phone base stations, three major mobile phone companies will report on the "Prefix Number Automatic" Service Connection Conditions in February 2021, and will guide you to start accepting early. doing.