Android

Does your phone support USB OTG? How to check, and turn it on

By Andre Gaz, developer of InspectCam™ · Published 1 August 2026 · Last updated 16 October 2026

You want to know whether you can plug something into your phone. A borescope, a flash drive, a card reader, a keyboard. And the first thing every search result tells you to do is install an app that will answer the question for you.

Don't. Those apps are wrong often enough to waste your afternoon, and there's a better test sitting in a drawer somewhere in your house.

Some phones have an OTG switch, and it turns itself off

Before you conclude anything from the test below, check this. On the Pixel 6a, Pixel 4a 5G and Galaxy S21 we test on there is no switch: OTG is simply on. But several manufacturers ship one, off by default, and it times out.

• vivo: Settings → More settings → OTG. vivo's own FAQ says the switch "will be turned off automatically if it is not used in 5 minutes", to save power.
• OPPO and realme: an OTG connection switch, reported to sit under Additional settings and to time out after about 10 minutes unused. realme's support advice is to unplug the adapter, search the phone's settings for "OTG connection", turn it on, and then connect the device.
• OnePlus: an OTG switch exists on several OxygenOS versions, where it is sometimes called OTG storage.

This matters more than it sounds. A phone with the switch off behaves exactly like a phone with no OTG at all: nothing happens when you plug something in. That is the single most common reason people conclude their phone can't do OTG when it can.

The mouse test

Any USB mouse will do. The oldest, cheapest, most forgotten one in the house is ideal, because it draws almost no power and speaks a protocol every version of Android has understood for over a decade.

1. Unlock the phone and leave it on the home screen.
2. Connect the mouse through your USB-C (or micro-USB) adapter.
3. Move the mouse and watch the screen.

A pointer appears and follows the mouse. Keep it moving while you look: Android hides the pointer when the mouse sits idle, so a still mouse can look like a dead one. That's it: your phone is acting as a USB host, supplying power and driving a peripheral. Everything else that needs OTG will work, subject to how much current it draws.

No cursor? Don't conclude anything yet. Read the next two sections first, because a charge-only cable produces exactly the same blank screen as a phone without OTG.

Why checker apps get it wrong

Here's the part nobody explains. An OTG checker app doesn't test the connection. It asks Android a question (roughly, "does this device declare the USB host feature?") and reports the answer back to you.

That declaration is a flag set by the manufacturer when the phone was built. It says what the phone is supposed to be able to do. It doesn't measure whether it actually does.

For OTG to genuinely work, four separate things all have to be true:

• The phone runs Android 3.1 or later, which is when the USB host API arrived. Every phone you'd plausibly own clears this.
• The USB hardware supports host mode.
• The kernel actually wires that hardware to the API. This is where budget devices quietly fail.
• The port supplies enough current to run whatever you plug in.

A checker app effectively tests the first one and takes the rest on trust. So you get both kinds of wrong answer: phones that report support and deliver nothing, and — less often, but it happens — phones that report nothing and work fine.

The flag isn't meaningless, though. An app that declares it needs USB host can be filtered out of Google Play on a phone that doesn't declare the feature, so a "no" can explain why a scope's app won't install.

The mouse doesn't care what the flag says.

The cable is lying to you

This is the single most common reason for a failed test, and it has nothing to do with your phone.

A USB cable can carry power without carrying data. The data lines are simply absent or unconnected. Cables bundled with power banks, cheap chargers, hotel freebies and most "fast charge" cables sold on price are wired exactly this way, and you cannot tell by looking, because the plug is identical.

Adapters fail too. If a second cable doesn't help, try a second adapter before blaming the phone.

How to check a cable in ten seconds: connect your phone to a computer with it and pull down the notification shade. If a USB notification appears and you can choose File transfer, the cable carries data. If the phone only charges and no USB option appears, it doesn't, and it was never going to run a mouse either.

Test with a known-good cable before you write off the phone. Ideally two.

What your result actually means

That last row matters more than it looks. Once a mouse works, you've eliminated the phone from the investigation entirely, which means every remaining problem lives in the cable, the scope, the app or the permission prompt.

Power is a separate question

Host mode working and your device working are not the same thing. A mouse draws almost nothing. A borescope with a ring of LEDs on the end draws continuously, and the brighter it gets the more it wants.

Phone ports have a hard current ceiling and will cut a peripheral off rather than exceed it. The signature is a device that runs for a few seconds and then disappears, or one that behaves at low brightness and drops at high.

Fixes to try: charge the phone first, since some phones limit port power when the battery is low. Remove any USB extension cable, because voltage sags over length and cheap extensions sag badly. For something genuinely hungry, use a powered OTG hub with its own supply, so the device draws from the wall rather than your battery.

If your phone really doesn't have it

Two cables in, nothing doing. It happens, mostly on entry-level and older budget models, and occasionally on carrier-locked variants where the OEM disabled it.

You can't add host mode. The capability lives in the hardware and the kernel, below anything you're allowed to touch. Some phones do have a switch that turns existing OTG on, as above, but no setting, app or permission adds it to a phone that lacks it. Every "enable OTG" app and root tutorial you'll find either does nothing or requires a custom kernel, which is a bigger project than the problem deserves.

What actually works:

• Use a Wi-Fi scope instead. It creates its own network and never touches USB, so host mode is irrelevant. You give up some latency and gain a battery to charge. Worth reading about why those drop connection before you buy one, because that catches everybody.
• Keep an old Android phone as a dedicated viewer. No SIM needed, no data plan, no calls. A phone that's been in a drawer since 2020 will very likely have OTG and makes a perfectly good scope screen that you won't mind dropping in a crawlspace.

iPhone doesn't work this way at all

OTG is an Android concept. On iPhone the equivalent question isn't whether the port can host a device (the USB-C models physically can) but whether iOS will talk to it, and for cameras the answer is no.

Apple restricts external USB video class camera support to iPads with USB-C connectors. iPhones are excluded, which is why a standard (UVC) USB borescope will draw power from an iPhone 15 or later and never show a picture. We've written that up separately, with Apple's own wording: do USB borescopes work with iPhone.

Questions people ask

How do I know if my phone supports USB OTG?

Plug in a USB mouse using an OTG adapter and watch for a cursor on screen. If one appears, your phone supports OTG. This is more reliable than a checker app, because it tests the whole chain (hardware, kernel and power) rather than reading a flag the manufacturer set.

Are USB OTG checker apps accurate?

Not always. They query whether the device declares USB host support, which is a manufacturer's statement of intent rather than a measurement. Phones exist that report support and deliver none, and a few that report none and work perfectly.

Can I enable USB OTG if my phone doesn't have it?

No. Host mode depends on the USB hardware and the kernel, both below the level any app can reach. No setting, app or permission adds it. A Wi-Fi device, or a spare Android phone that does have OTG, is the practical route.

Why does my OTG cable work for charging but not for devices?

Because power and data travel on different wires, and plenty of cables carry only power. Test the cable by connecting your phone to a computer: if a USB notification appears on the phone and you can choose File transfer, the data lines are intact.

Does the iPhone have USB OTG?

Not as a concept. USB-C iPhones can supply power to accessories, but iOS does not expose external USB cameras to apps on iPhone. Apple limits that to iPads with USB-C. A standard (UVC) USB borescope will power up on an iPhone and still show nothing. Scopes sold specifically for iPhone work only in their maker's app.

My phone recognises a flash drive but not my borescope. Why?

Host mode is working, so the phone isn't the problem. The likely causes are a charge-only cable, a scope that uses a proprietary protocol rather than standard UVC, a dismissed USB permission prompt, or a device drawing more current than the port will give.

Tested this on a phone that behaved differently from what's described? Tell us the model. Device-specific quirks are what makes this page worth keeping.