> ## Documentation Index
> Fetch the complete documentation index at: https://support.onroamly.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Before you install: four quick checks

> Be on Wi-Fi, use an unlocked phone, install on the phone you'll travel with, and leave the eSIM switched off until you land.

Installing takes about a minute. These four checks stop the handful of things that can go wrong.

<Steps>
  <Step title="Be online">
    Your phone downloads the eSIM from the network, so it needs an internet connection: home Wi-Fi, your normal mobile data, or airport Wi-Fi all work. Home is easiest.
  </Step>

  <Step title="Use an unlocked phone">
    A phone that's locked to a carrier can't use another provider's eSIM. Most phones bought outright are unlocked; if yours came on a plan, check with your carrier. See [Does my phone support eSIM?](/getting-started/does-my-phone-support-esim) for the full list of supported models.
  </Step>

  <Step title="Install on the phone you'll travel with">
    An eSIM can only be installed on one phone. Once it's on a phone it stays there, so install it on the one you're taking. Buying for someone else? Install it on their phone with the QR code — see [Can I use my eSIM on more than one device?](/managing/multiple-devices)
  </Step>

  <Step title="Leave it switched off until you land">
    Installing doesn't use any of your plan. Most plans only start counting when the eSIM first connects to a network at your destination, so once it's installed, leave the Roamly line switched off and turn it on when you arrive. See [When to buy, install and switch on](/getting-started/when-to-buy-install-and-switch-on).
  </Step>
</Steps>

<Note>
  A few plans say **Starts on installation** on the plan page. For those, the days start counting as soon as the eSIM is installed, so install them close to your departure.
</Note>

## Ready?

* [Install with the Roamly iPhone app](/installing/iphone/app) or [from the website on iPhone](/installing/iphone/website)
* [Install with the Roamly Android app](/installing/android/app) or [from the website on Android](/installing/android/website)
* Installing on a different phone than the one you're signed in on? Use the QR code: [iPhone](/installing/iphone/qr-code-or-manual) · [Android](/installing/android/qr-code-or-manual)
* Already installed and about to land? [Just landed? How to activate your eSIM](/installing/when-you-land)