Ajit kumar

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[Ajit kumar @ajitcodes]

These 9 lectures from Stanford University are the BEST for anyone wanting to learn and understand LLMs in depth

Lecture 1 - Transformer: https://t.co/cVdYFH3S4Y

Lecture 2 - Transformer-Based Models & Tricks: https://t.co/Y5NMU4gukB

Lecture 3 - Tranformers & Large Language Models: https://t.co/l1g10v5Geo

Lecture 4 - LLM Training: https://t.co/Yns6HyfhJE

Lecture 5 - LLM tuning: https://t.co/19B5gUR56K

Lecture 6 - LLM Reasoning: https://t.co/YAMRpvjvji

Lecture 7 - Agentic LLMs: https://t.co/xo9oWaeO5p

Lecture 8 - LLM Evaluation: https://t.co/hPoBaT0g2J

Lecture 9 - Recap & Current Trends: https://t.co/knCs62eb42

Start understanding LLMs in depth from the experts. Go through each step-by-step video

Start understanding LLMs in depth from the experts. Go through each step-by-step video

[Ajit kumar @ajitcodes]

These 9 lectures from Stanford University are the BEST for anyone wanting to learn and understand LLMs in depth

Lecture 1 - Transformer: https://t.co/cVdYFH3S4Y

Lecture 2 - Transformer-Based Models & Tricks: https://t.co/Y5NMU4gukB

Lecture 3 - Tranformers & Large Language Models: https://t.co/l1g10v5Geo

Lecture 4 - LLM Training: https://t.co/Yns6HyfhJE

Lecture 5 - LLM tuning: https://t.co/19B5gUR56K

Lecture 6 - LLM Reasoning: https://t.co/YAMRpvjvji

Lecture 7 - Agentic LLMs: https://t.co/xo9oWaeO5p

Lecture 8 - LLM Evaluation: https://t.co/hPoBaT0g2J

Lecture 9 - Recap & Current Trends: https://t.co/knCs62eb42

Start understanding LLMs in depth from the experts. Go through each step-by-step video

Start understanding LLMs in depth from the experts. Go through each step-by-step video

[Ajit kumar @ajitcodes]

A woman walked into Verizon ready to change her phone number after 12 years.

She was getting 47 spam calls a week. Robocalls at 7am. Scam texts during meetings. Voicemails in Mandarin selling fake insurance.

She had blocked 200+ numbers. Reported them to the FTC. Downloaded three different spam apps. Nothing worked.

The calls kept coming.

She filled out the number change form and slid it across the counter: "I just want a clean start."

The rep looked at the form, then back at her phone.

"Before you lose your number forever, let me show you something. Your number isn't burned. It's exposed. There are 18 ways they're tracking you right now. The carriers won't tell you this because the data broker ecosystem pays them. Let's fix it."

Here's what he showed her in the next 11 minutes:

[Ajit kumar @ajitcodes]

That's wrap

If you found this thread helpful:

Follow me @ajitcodes for more such content.

[Ajit kumar @ajitcodes]

18. The Hidden Carrier Spam Filter

The Situation: You pay AT&T, Verizon, or T-Mobile $80 to $120 a month for premium 5G cell service. Yet, you feel like they are doing nothing to stop the onslaught, leaving you to rely on ignoring your phone or downloading third-party tools.

The System: The major telecom carriers actually possess massive, incredibly powerful network-level blocking capabilities utilizing protocols like STIR/SHAKEN (which verifies the cryptographic signature of the caller). However, they intentionally do not enable the strictest filters by default. They are terrified of the legal liability and customer rage of a "false positive", accidentally blocking a call from your doctor, your kid's school, or an emergency dispatcher. Because of this fear, they let the spam pass through to your device and put the burden of blocking it on you.

Why it works: You have to force their hand. Download your specific carrier's proprietary, free security app (Verizon Call Filter, AT&T ActiveArmor, or T-Mobile Scam Shield). Open the app, dive into the settings, and manually override their conservative defaults. Toggle the block settings to "Maximum," "High Risk," or "Send All Spam to Voicemail." This intercepts the call at the network tower before it ever reaches your phone's physical hardware.

The Takeaway: Make the telecom giants do the heavy digital lifting that you pay them for every single month.

[Ajit kumar @ajitcodes]

19. The "Clean Start" Illusion (The Conclusion)

The Situation: After 11 minutes of listening to this, the woman stared at the Verizon rep, completely overwhelmed but finally understanding the mechanics of the machine that was hunting her. She looked down at the number change form she had filled out earlier. She still felt the urge to just burn it all down and start over with a brand new set of digits.

The System: The rep gently tapped the paperwork on the counter. "If I process this form and give you a new number today," he explained, "it is not actually 'new.' It is a recycled number from someone who likely just abandoned it for the exact same reasons you are standing here right now. You are inheriting their spam."

But it gets worse. Even if the number was miraculously clean, the moment she updated her bank app, ordered a package from Amazon, or logged into her social media on the same physical device, the data broker algorithms would instantly link her "new" number to her old identity profile. The digital connective tissue is too strong. Within 72 hours, the robocalls would find her all over again. Changing your number doesn't erase your digital footprint; it just adds a new address to the same old file.

Why it works: You cannot outrun the modern data economy by simply changing your digits; you can only outsmart it by fundamentally changing your digital behavior. The woman realized that by implementing the 18 steps the rep had just shown her, she wasn't just downloading a band-aid app she was methodically starving the data broker ecosystem of the behavioral signals it needed to target her. She was closing the loopholes, locking the digital doors, and removing herself from the menu. She was becoming a digital ghost.

The Takeaway: The woman slowly reached out across the glass counter, picked up the number change form, and tore it in half. She didn't need a new number. She just needed a new defense. She picked up her phone now locked down, silent, and fortified and walked out of the store. Her phone didn't ring once on the drive home.

Privacy isn't a setting you are given by default. It is a perimeter you have to aggressively take back.

[Ajit kumar @ajitcodes]

17. The FTC Do Not Call Registry Paradox

The Situation: Desperate to stop the madness, you proudly register your phone number on the federal government's National Do Not Call (DNC) list. You sit back, assuming the law will protect you and the spam will finally stop.

The System: The DNC list was designed in 2003 and only stops legitimate, law-abiding American corporations who actually fear FTC fines. Illegal, offshore criminal syndicates operating out of unregulated call centers do not care about American laws. In fact, it is widely known in the cybersecurity community that hackers steal downloaded copies of the DNC list and sell it to scammers. Why? Because the DNC list is essentially a massive, verified, pristine directory of highly active, human-operated phone numbers. You essentially raised your hand and said, "I am here."

Why it works: You should still register for the DNC list to kill the annoying but legal corporate telemarketing calls, but you must completely adjust your expectations. Do not rely on it for security. Rely entirely on your OS-level firewalls (Tip #4) for the real, malicious threats.

The Takeaway: Rules only stop rule-followers. To a scammer, a government protection list is just a highly curated menu.

[Ajit kumar @ajitcodes]

16. The Data Broker Aggregation

The Situation: You assume that the scammers calling you are just running random number generators, hoping to get lucky by dialing every combination of digits. You think you are completely anonymous.

The System: The reality is much darker. Multi-billion dollar data broker companies (like Whitepages, Spokeo, LexisNexis, and Radaris) have legally scraped decades of your public records. They take your property deeds, voter registrations, marriage licenses, and court records, and they inextricably link them to your cell phone number. They package this massive, detailed dossier and sell it to anyone with a credit card. Scammers buy these profiles to craft highly targeted, personalized attacks that mention your home address, your age, and your relatives' names to terrify you into compliance.

Why it works: You must actively fight to scrub your footprint. Use a professional data removal service (like DeleteMe, Incogni, or Kanary) to constantly monitor and delete your profiles, or spend a weekend manually submitting CCPA/GDPR opt-out requests to the top 20 data brokers yourself.

The Takeaway: You are not a random, anonymous target. You are a highly detailed, legally purchased profile. Erase it.

[Ajit kumar @ajitcodes]

15. The "Smishing" Link Payload

The Situation: You receive a terrifying text message stating that your bank account is frozen, your Netflix is suspended, or a package is undeliverable. It includes a short link to "verify your identity." You are smart enough not to type in your password, but you click the link just to see what the website looks like.

The System: The attack is called "Smishing" (SMS Phishing), and the payload is delivered the millisecond you click. That short link is uniquely generated and tied exclusively to your phone number. When you click it, a tracking pixel fires on the scammer's server. Without you entering a single keystroke, you have confirmed to the scammer that your number is active, tied the phone number to your current IP address/physical location, logged your exact device type (iPhone vs Android), and recorded your browser version.

Why it works: Never, under any circumstances, click a link inside an unsolicited text message. If you are genuinely worried about your bank or a package, close the text app, open your web browser, and manually type in the official, verified URL of the company yourself.

The Takeaway: You don't have to fill out a form to be hacked. The click itself is the compromise.

[Ajit kumar @ajitcodes]

14. The Venmo/CashApp Public Ledger

The Situation: You split a pizza with friends, pay your roommate for utilities, or buy a coffee using Venmo or CashApp. You leave the transaction privacy settings on the default "Public" mode because it's fun to see what emojis your friends are using.

The System: Financial applications with public feeds are heavily monitored and scraped by sophisticated social engineering scammers. By analyzing who you pay, who pays you, and the frequency of those transactions, they map out your intimate social graph. They cross-reference these names with data broker sites to find your phone number. Suddenly, you get an urgent, panicked text message from an unknown number posing as your best friend "Mike" who you just publicly paid for pizza yesterday claiming he dropped his phone in a lake and needs emergency cash wired to a new account.

Why it works: Go into your financial apps and set all past and future transactions to strictly "Private." Furthermore, remove your phone number from public visibility or searchability within the app's privacy settings.

The Takeaway: Your financial network is a literal roadmap to your real life. Hide it immediately.

[Ajit kumar @ajitcodes]

13. The Email Signature Scraping

The Situation: You are a dedicated professional. To make sure clients can always reach you, you put your direct mobile phone number at the very bottom of your email signature, alongside your title and company logo.

The System: Think about the lifecycle of an email. Over the years, your emails are replied to, forwarded, BCC'd, and stored in thousands of different inboxes across dozens of companies. It is a mathematical certainty that at least one of those people will have their email server hacked or compromised. When hackers breach an Exchange server, they deploy scraping bots that read every single stored email specifically looking for phone numbers and email addresses to steal. Your number is extracted from the signature block and sold in bulk.

Why it works: Remove your direct, personal cell line from your public email signature immediately. Use a main company switchboard line, a dedicated virtual VoIP number, or better yet, a clickable meeting booking link (like Calendly) that requires them to schedule time without ever seeing your actual digits.

The Takeaway: Your professional courtesy is an absolute gold rush for scraping bots.

[Ajit kumar @ajitcodes]

11. The WhatsApp/Telegram Sync Leak

The Situation: You use secure, end-to-end encrypted messaging apps like WhatsApp, Telegram, or Signal because you care about privacy. However, you leave all the app settings on their factory defaults.

The System: End-to-end encryption only protects the contents of your messages, not your metadata. Scammers write automated scripts to generate millions of random phone numbers and ping them continuously against WhatsApp and Telegram servers via their APIs. Because your settings are on default, anyone in the world who pings your number can instantly see your high-res "Profile Picture," your "Last Seen" online status, and your "About" bio. This instantly verifies your number is active, tags your face to the number, and allows them to reverse-image-search you to find your LinkedIn or Facebook.

Why it works: Open your messaging app's privacy settings the moment you read this. Change your "Profile Photo," "Last Seen," "Online Status," and "About" settings to "My Contacts Only."

The Takeaway: Encryption secures the conversation. You have to secure the perimeter yourself.

[Ajit kumar @ajitcodes]

12. The "Hello? Hello?" Voice Print

The Situation: You answer a call from an unknown number because you are expecting a delivery. You hold the phone to your ear. There is nothing but dead air. Annoyed, you say, "Hello? Who is this? Yes, I'm here."

The System: This is not a bad connection. Scammers use deliberate, programmed silence to force the human to speak first. They are actively recording the line. The moment you speak, especially if you say a clear word like "Yes" or "Hello," they capture a high-quality audio sample of your vocal frequencies. They use readily available AI tools to clone your voiceprint. They will then use this synthetic clone to bypass voice-biometric security at your bank, or call your grandparents sounding exactly like you, begging for bail money.

Why it works: If you absolutely must answer a call you aren't sure about, hold the phone to your ear and say absolutely nothing. A real human on the other end will eventually say "Hello?" A bot is programmed to wait for audio input; if it gets 3 seconds of dead silence, it assumes it hit a dead line and will automatically hang up.

The Takeaway: In the digital age, he who speaks first, loses the data.

[Ajit kumar @ajitcodes]

10. The "Press 1 to Speak to an Agent" Mistake

The Situation: You answer a robocall by mistake. A recorded voice tells you about an expired car warranty. You get furious. The recording says, "Press 1 to speak to an agent to be removed from our list." You smash the '1' key, ready to scream at a human being.

The System: You just fell for a devastating compliance trap. By pressing a button on your dial pad, you interacted with their Interactive Voice Response (IVR) system. You signaled to the algorithm that you are a highly reactive, compliant individual who actively listens to and follows audio prompts. While you do get transferred to a human, your number is simultaneously escalated on the backend to a "premium, highly gullible" scam list. You will now be targeted by much more sophisticated, high-effort scams.

Why it works: If you accidentally answer a spam call and realize it's a recording, hang up immediately. Do not navigate their menus. Do not attempt to reason with, yell at, or outsmart a machine.

The Takeaway: Your anger is just another measurable metric to them. Keep your emotions to yourself.

[Ajit kumar @ajitcodes]

8. The Virtual Number Shield

The Situation: You are trying to get a quick quote for car insurance, sign up for a local gym trial, or download a whitepaper online. The web form demands a phone number before you can click "Submit." You type in your cell number.

The System: Ninety percent of these sites are not actually service providers; they are "lead generation" fronts. Their entire business model is to harvest your phone number and sell it as a "hot lead" to 50 different aggressive contractors, insurance agents, or salespeople within milliseconds of you hitting submit. Your phone will start ringing before the webpage even finishes loading.

Why it works: You need to compartmentalize your digital life. Download an app like Google Voice, Burner, or Hushed immediately. Generate a secondary, disposable "junk" phone number. Give this burner number to any business, web form, or person you do not deeply, personally trust. You can mute the burner app entirely and check it only when you want to.

The Takeaway: Treat your real cell phone number exactly like your Social Security Number. Protect it ruthlessly.

[Ajit kumar @ajitcodes]

9. The App Permissions Sweep

The Situation: You are bored and download a free flashlight app, a custom keyboard, a horoscope reader, or a cheap mobile game. Upon opening it, a pop-up asks for access to your Contacts. You blindly click "Allow" just to get to the game faster.

The System: The developer's actual business model has absolutely nothing to do with the game you are playing. They are a data brokering front. The second you hit "Allow," their script scrapes your entire address book. They vacuum up your personal phone number, along with the names, numbers, and emails of your family, your boss, and your friends. They bypass any privacy settings you have by exploiting your permissions, and they sell the entire network graph.

Why it works: You must audit your phone's app permissions today. Go to Settings > Privacy > Contacts. You will be horrified by what has access. Turn off access for literally anything that isn't a dedicated, trusted messaging or phone app. A calculator does not need to know who your mother is.

The Takeaway: Free apps are never actually free. You are paying for them with your entire network's private data.

[Ajit kumar @ajitcodes]

7. The Single-Sign-On (SSO) Tax

The Situation: For convenience, you use your primary, real phone number as your 2-Factor Authentication (2FA) recovery method for Twitter, Facebook, Instagram, and various retail websites.

The System: Major platforms experience massive data breaches constantly. When a platform is compromised, your phone number is leaked directly alongside your email address and hashed passwords. This data is instantly dumped into massive, searchable databases on the dark web used by SMS scammers. Furthermore, relying on SMS for security leaves you vulnerable to "SIM swapping," where a hacker convinces your carrier to port your number to their phone, giving them access to all your bank codes.

Why it works: Stop using text messages for security. Switch to a dedicated Authenticator app (like Authy, Duo, or Google Authenticator) or a physical hardware key (like a YubiKey) for your 2FA. Go into your social media profiles today and scrub your phone number from the account settings entirely.

The Takeaway: SMS is not a security feature. It is a massive exposure point.

[Ajit kumar @ajitcodes]

A woman walked into Verizon ready to change her phone number after 12 years.

She was getting 47 spam calls a week. Robocalls at 7am. Scam texts during meetings. Voicemails in Mandarin selling fake insurance.

She had blocked 200+ numbers. Reported them to the FTC. Downloaded three different spam apps. Nothing worked.

The calls kept coming.

She filled out the number change form and slid it across the counter: "I just want a clean start."

The rep looked at the form, then back at her phone.

"Before you lose your number forever, let me show you something. Your number isn't burned. It's exposed. There are 18 ways they're tracking you right now. The carriers won't tell you this because the data broker ecosystem pays them. Let's fix it."

Here's what he showed her in the next 11 minutes:

[Ajit kumar @ajitcodes]

6. The "Neighbor Spoofing" Psychology

The Situation: Your phone rings. You look down and see a number that shares your exact local area code, and even the next three digits (the prefix). You answer it, assuming it must be your local pharmacy, your kid’s school, or a neighbor down the street.

The System: Scammers don't use real phones; they use Voice over Internet Protocol (VoIP) software running on servers halfway across the world. They use dynamic spoofing algorithms to mask their real origin. The software analyzes your phone number and automatically generates a fake caller ID that matches your prefix. They are weaponizing the psychology of proximity. They know humans are wired to trust things that look familiar and local.

Why it works: You have to re-train your brain to recognize the pattern. If you don't have the number explicitly saved in your contacts, a hyper-local similarity is actually a massive red flag, not a green light. Let it go to voicemail. A real neighbor will leave a message.

The Takeaway: Proximity is the oldest and most effective trick in the social engineering playbook.

[Ajit kumar @ajitcodes]

5. The Loyalty Program Data Leak

The Situation: You are checking out at the grocery store, the pharmacy, or a sporting goods store. The cashier asks for your phone number to save you $1.50 on paper towels or to give you "rewards points." You punch it into the keypad without a second thought.

The System: Giant retail corporations aren't giving you a discount out of the kindness of their hearts; they are buying your consumer data at a massive discount. They tie your private phone number to your hyper-specific purchasing habits, dietary choices, and medical needs. They then sell this comprehensive profile to massive data aggregators like Acxiom or Experian. Once your number enters this aggregated ecosystem, it becomes de facto public domain for aggressive telemarketers.

Why it works: Stop trading your long-term digital privacy for a 5% discount on snacks. Start using a fake number at the register. Use your childhood landline that no longer works, a random local business number, or a dedicated, free Google Voice number that you never actually check.

The Takeaway: Your data is worth infinitely more than their "exclusive" rewards.

[Ajit kumar @ajitcodes]

4. The Native OS Firewall

The Situation: You rely on expensive, third-party apps from the App Store to block incoming spam calls, but your phone is still ringing during dinner. You feel completely helpless.

The System: Both Apple and Google have built incredibly powerful, deep, hardware-level firewalls straight into your phone’s operating system but they are turned off by default. Data brokers and telemarketers are terrified of these features. Apple calls it "Silence Unknown Callers." Android calls it "Block unknown callers."

Why it works: When you toggle this switch on, the phone checks the incoming caller ID against your saved contacts, your recent outgoing calls, and your email/Siri suggestions. If there is no match, the phone never even rings. The call is instantly and silently routed to voicemail. You will simply see a silent notification pop up. The scammer's autodialer registers a "no answer" and moves on.

The Takeaway: Lock the digital front door. Make the scammers use the mail slot.

[Ajit kumar @ajitcodes]

3. The Voicemail Greeting Goldmine

The Situation: You set up your voicemail years ago to be polite and professional. It says, "Hi, you've reached Sarah Smith. I can't come to the phone right now, but please leave a message..."

The System: Advanced robocalls are no longer just leaving pre-recorded audio; they are equipped with voice-recognition and scraping software. When they hit your voicemail, they digitally record your greeting. In just a few seconds, they scrape your unique voice data, confirm your gender, and verify your exact full name. This enriched data profile is then repackaged for devastating spear-phishing attacks. They will use your name to target your elderly relatives, claiming "Sarah" is in trouble.

Why it works: You are giving them the keys to your identity for free. Switch back to the robotic, default carrier greeting immediately. "The number 5-5-5-0-1-9-9 is not available." Give the machines absolutely zero personalized data, zero names, and zero voiceprints to scrape.

The Takeaway: If the algorithm doesn't know who you are, the scammer doesn't know how to manipulate you.