A strange number sent a string of question marks.

Does the subject want to ask, "What is a string of question marks sent by strange numbers?" Fraudulent information, junk information.

1. Fraud information: Some fraud gangs will send question marks or other garbled information via SMS to confuse or deceive users and then commit fraud.

2. Spam: Some advertisers or spammers will send question marks or other spam messages through SMS to promote or publicize their products or services.