The interview was only notified by SMS.

In this case, you can be a little cautious.

If it is normal, it is the information given by the headhunter, but I want you to explain his phone number as an introducer.

If it's not normal, it may be a deliberate trap to guide you to make that call.

Is there any information about job interview in the text message? Where is it? Company name? You can take this information and search online to see if it is normal.