Blog | G5 Cyber Security

Spoofed Calls & Spam Texts: A Simple Guide

G5 Cyber Security

TL;DR

Caller ID spoofing lets scammers hide their real number and pretend to be someone else, often used for fraud. Spam texts are sent in bulk using automated systems. Protecting yourself involves being cautious about unknown numbers, reporting suspicious activity, and using call blocking/filtering tools.

How Caller ID Spoofing Works

  1. What is Caller ID? Your phone network normally shows the number of the person calling you. This information comes from the caller’s provider.
  2. Spoofing Explained: Scammers use software or services to change the number that appears on your Caller ID. They can make it look like they’re calling from a local business, a government agency, or even *your own* number!
  3. Why do they do it? To trick you into answering the phone and giving them information (like bank details) or to get you to download malware.
  4. Technical Details: Voice over Internet Protocol (VoIP) services are often used. These allow users to make calls using an internet connection, and easily manipulate caller ID data. 
    # Example of a simplified VoIP configuration (not actual code for spoofing)
sip_user=yourusername
sip_server=voip.provider.com
caller_id=<spoofed_number>
  5. Legality: Caller ID spoofing is illegal in many countries when used with the intent to defraud, cause harm, or obtain something of value.

How Spam Texts Work

  1. Bulk SMS Gateways: Spammers use services called SMS gateways to send thousands of texts at once. These are often legitimate businesses that get abused.
  2. Data Collection: They obtain phone numbers from data breaches, online forms, or by randomly generating them.
  3. Automated Systems: Scripts and software automatically send the same message to many different numbers. 
    # Example of a simplified Python script using an SMS API (not actual spam code)
from twilio.rest import Client
client = Client(account_sid, auth_token)
message = client.messages.create(
to="+447xxxxxxxx", 
from_="+15558675309", 
body="Spam message content")
  4. Phishing & Malware: Texts often contain links to fake websites (phishing) that steal your login details or download malware onto your phone.
  5. SIM Swapping: A more advanced attack where scammers convince your mobile provider to transfer your number to a SIM card they control, allowing them to intercept texts and calls.

How to Protect Yourself

  1. Don’t Answer Unknown Numbers: If you don’t recognise the number, let it go to voicemail.
  2. Be Wary of Requests for Personal Information: Legitimate organisations will *never* ask for sensitive details (bank account numbers, passwords) over the phone or by text.
  3. Don’t Click Suspicious Links: Even if a text looks like it’s from someone you know, be careful about clicking links.
  4. Report Spam Texts: Forward spam texts to 7726 (SPAM) on your mobile phone. This helps network providers identify and block spammers.
  5. Use Call Blocking Apps: Many apps can automatically block known scam numbers or filter out suspicious calls.
    • Truecaller
    • Hiya
    • Your phone’s built-in blocking features
  6. Contact Your Mobile Provider: Report spoofed calls and spam texts to your provider. They may be able to take action.
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