No. That was not a legitimate Microsoft support number based on the described behavior.
Key signs of a tech support scam:
- Microsoft does not make unsolicited phone calls to offer technical support.
- Genuine Microsoft error and warning messages never include a phone number to call.
- Fake support scam pages often use alarming pop-ups, sounds, full-screen loops, and Microsoft branding to pressure a call.
What happened fits a common browser-based tech support scam, not a real Microsoft system error. The fact that the message appeared while browsing, trapped the browser in a loop, and pushed a phone number is a strong indicator.
What to do now:
- Do not call that number.
- If the pop-up appears again, close the browser. If the mouse does not work, press ALT+F4.
- If the browser will not close, restart the PC.
- When the browser reopens, do not restore the previous session if prompted.
- Run a full scan with Microsoft Defender Antivirus.
- Apply available security updates.
- Report the scam at Submit report or www.microsoft.com/reportascam.
If any information was already given to the caller or remote-access software was installed:
- Uninstall the software they asked to install.
- Change passwords.
- Monitor sign-in activity.
- Contact the bank or card issuer if any payment details were shared.
- Consider resetting the device to a factory state, because remote access can leave malware or persistence behind.
The longer Dell startup sequence after unplugging and restarting does not by itself confirm corruption. The supported guidance is to scan the device with Microsoft Defender Antivirus and install security updates.