What do you mean by unknown?

1. The main reason should be the inconsistency of communication networks. Although the three major domestic operators all have their own independent communication networks, the interworking frequency bands and number segments between operators are basically the same, so the incoming number can be displayed when calling each other.

2. There is also to see if your mobile phone card has caller ID. If so, confirm whether the other party is calling through VoIP. Some VoIP phones do not display the incoming number.

3. It may be the other party's number. The other party may have used some computer software or the free calling function of a communication App to call you. This won't deduct your money.

4. Harassment calls are generally made by using VoIP software and have not been registered on the operator's server. Caller display service is a service that can automatically display the caller's number on the display screen of the phone, and can know the caller's phone number in advance.

5. If the APP such as TouchPal VoIP is initiated by the calling party, the technical center will dial the called party. At this time, the caller ID is unknown, but the virtual number can be realized through technology, which generally requires extra payment in VoIP.

Extended data:

1232 1 Reporting Center for Bad Internet and Spam Information (hereinafter referred to as "1232 1 Reporting Center") is a reporting agency entrusted by the Ministry of Industry and Information Technology in internet society of china. Responsible for assisting the Ministry of Industry and Information Technology to accept, investigate, analyze and investigate bad and junk information in various forms of information communication networks and telecommunications services such as the Internet, mobile telephone networks and fixed telephone networks.

Reporting method:

(1) wechat: follow 1232 1 wechat WeChat official account "1232 1 reporting center", click "I want to report" or directly send text, voice and screenshots to report;

(2) Weibo: Please pay attention to "1232 1 reporting center" and send a private message or @1232/reporting center to report;

(3) SMS: You can send SMS to the five-digit short number "1232 1" to report spam messages. Manually enter the report number (that is, the sender's spam message number, which is very important) in front of the message you want to report, and then add a * sign to separate the message content, and then send it to the five-digit short number of "1232 1";

(4) MMS: enter the report number in the "title bar" of the MMS you want to report, then add "*" to separate the following MMS titles, and then send them to "12321";

(5) Tel: 010-12321;

(6) Website: www.12321.cn;

(7) E-mail: abuse @ 1232 1.cn.

(8) mobile App:? (Currently only Android phones are supported)