What does *#21 do on your phone?

What Does *#21# Do on Your Phone?

If you’ve ever wondered what dialing *#21# does on your phone, you’re not alone. This simple code is a built-in feature on most mobile devices, and it’s designed to check your call forwarding status at a glance.

When you enter *#21# and press the call button, your phone quickly retrieves information about whether your calls, text messages, or even data connections are being forwarded to another number. It’s a quick way to see if call forwarding is active—without digging through settings menus.

For example, if your phone is set to forward incoming calls to voicemail or another line when you’re busy or out of coverage, this code will reveal that setup. The same goes for SMS and data forwarding, though availability may vary depending on your carrier and device.

One common myth is that *#21# can detect if your phone has been hacked or is being secretly monitored. That’s not true. While it shows forwarding settings—which could theoretically be changed by someone with access to your device—it doesn’t uncover spyware or unauthorized surveillance.

This code works on both Android and iPhone, as it’s part of a universal set of USSD (Unstructured Supplementary Service Data) codes supported by GSM networks. It’s fast, free, and doesn’t require internet access.

So, next time you're curious about where your calls are going—or just want to double-check your settings—try *#21#. It’s a small but handy tool tucked right into your phone’s dialer. Just remember, it only shows the current status; it won’t fix anything, but it can help you spot settings you didn’t enable yourself.