8 Fixes to Wi-Fi Calling Error ER01 Invalid Certificate

Wi-Fi calling excludes the need to use a cellular network. Especially for smartphone users, this technology is a boon. It helps users operate the basic calling and texting functions of their smartphones from locations where cellular networks are hard to receive. However, amid so many perks of Wi-Fi calling, smartphone users can sometimes receive Wi-Fi calling error ER01 invalid certificate due to a number of reasons. If you are someone dealing with the same issue on your phone, then we have bought a perfect guide for you.

8 Fixes to Wi-Fi Calling Error ER01 Invalid Certificate

How to Fix Wi-Fi Calling Error ER01 Invalid Certificate

Error ER01 on a smartphone indicates issues with connectivity and functionality with Wi-Fi calling feature. The error is usually encountered by organization workers who try to connect to other people over the company’s Wi-Fi network. This can be due to the IT department blocking employee activity on their company’s network. For the home Wi-Fi network, other reasons that can trigger the error include:

  • Improper installment of your home Wi-Fi network.
  • Disabled Wi-Fi calling feature.
  • Outdated device software.
  • Problems related to the Wi-Fi router.
  • Problem with network settings of the smartphone.

Method 1:Basic Troubleshooting Methods

1. Restart Router and Phone

The first measure to resolve error ER01 involves restarting your router or phone. Usually, the issue lies with the device or router that you use due to minor issues. These glitches can be resolved by simply restarting these devices. To restart your home router, you can follow the steps mentioned below:

1. Locate the power button at the back of your router and press it.


2. Now, disconnect the power cable of your router and wait till the power is off.

3. After some time reconnect the power cable and switch on the router.

4. Let the connection re-establish and try signing in.

To restart your Android device, you can refer to our guide, How to Restart or Reboot Your Android Phone?

2: Toggle Airplane Mode On and Off 

You can try turning on airplane mode on your device which will block the cellular network and stop your SIM card from working. Check the steps below to follow this method on your phone:

Note: Steps in the doc are performed on Vivo 1920 Android phone.

1. Open your Android Settings app.

2. Launch the Other networks & connections option in it.

3. Now, toggle on the option for Airplane mode.

4. After some time, toggle off Airplane mode.

Toggle off Airplane mode

The above steps will reset your cellular network and fix the Wi-Fi calling error as well.

Also Read: How to Stop WiFi Turn On Automatically on Android

3. Use Working Wi-Fi Connection

If you still have not been able to fix Wi-Fi calling error invalid certificate then you must ensure that your Wi-Fi is enabled and working. On connecting to a good Wi-Fi network, you will be able to operate Wi-Fi calling with excellent cellular signals. To enable Wi-Fi on your device, follow the steps as instructed below:

1. On opening the Settings app of your device, tap on Wi-Fi.

2. Now, toggle on the Wi-Fi button.

Toggle on the Wi-Fi button

3. Tap on your preferred network from the Available networks list.

4. Now, check the Signal strength of your Wi-Fi network and browse the internet to ensure it is working fine.

Method 2: Enable Wi-Fi Calling

To ensure you can call and text over a Wi-Fi network on your device, you need to make sure Wi-Fi calling is enabled in settings. This will help you resolve error 01 invalid certificate that often comes up due to connectivity issues. To enable Wi-Fi calling, follow the steps mentioned below:

1. Launch Settings of your Android phone and navigate to the search bar in it.

2. Type Wi-Fi calling in the search bar and press Enter.

Type Wi-Fi calling in the search bar and press Enter

3. Now, tap on the Wi-Fi calling option.

4. Finally, slide the toggle to turn on the Wi-Fi calling.

Method 3: Remove and Reinsert SIM Card

If you are unable to fix Wi-Fi calling error ER01 invalid certificate with the help of the above-given methods, you can try this simple workaround that involves removing and then reinserting the SIM card in your Android phone. Follow the steps below to place the SIM properly in your phone slot after removing it:

  • Navigate to the SIM tray on your Android phone and insert a pin in the hole to open the tray.
  • Now, take the SIM card out of the tray.
  • Next, place the SIM card properly in the tray and push it back into the phone.
  • Finally, turn on your device and check if error ER01 has been resolved now.

Also Read: Fix WiFi Authentication Error on Android

Method 4: Update Android

There can also be an issue with the software of your Android device due to which you are facing a Wi-Fi calling error invalid certificate. To rule out this possibility, you must update your Android device to the latest version. Refer to our guide on How to Manually Update Android To Latest Version to properly attempt this method.

Update Android

Method 5: Reset Network Settings

One of the last methods that you can opt for in order to resolve error ER01 is to reset network settings. This method will automatically reset network adapters on your device which turns out to be very beneficial in resolving errors related to connectivity. Now, refer to the steps below to reset network settings on Android device:

1. Open the Settings app and launch System management on your phone.

2. Next, tap on Backup & Reset.

3. Now, tap on Reset network settings in the next menu.

Tap on Reset network settings. 8 Fixes to Wi-Fi Calling Error ER01 Invalid Certificate

4. Tap on Reset settings on the screen.

5. Once done, reconnect to your Wi-Fi network and check if the error has been resolved.

Also Read: How To View Saved WiFi Passwords on Windows, macOS, iOS & Android

Method 6: Try Different Wi-Fi Network

The last method that can help you fix error 01 invalid certificate is to try a different Wi-Fi network altogether. In case none of the methods mentioned above has helped you in fixing the error, there is a high chance the problem lies with your Wi-Fi network. Therefore, to resolve it try connecting to some other Wi-Fi network and check if the Wi-Fi calling works or not. You can also try getting a new router if changing the network does not work.

Frequently Asked Questions (FAQs)

Q1. How can I enable Wi-Fi calling?

Ans. You can enable Wi-Fi calling from the settings of your device. You can also refer to Method 4 to enable the feature on your Android phone.

Q2. Why is Wi-Fi calling feature not working on my phone?

Ans. If the Wi-Fi calling feature is not working on your phone, then it can be due to the setting being turned off. The error can also arise from an issue with your Wi-Fi network.

Q3. Why is Wi-Fi calling used?

Ans. Wi-Fi calling is used to make calls and send texts from a smartphone over the internet. This feature is extremely useful during no cellular network.

Q4. Is there any disadvantage of Wi-Fi calling?

Ans. There are some disadvantages of Wi-Fi calling like poor signal strength, poor voice call quality, and dropped calls.

Q5. Which devices support the Wi-Fi calling feature?

Ans. Smartphones like Samsung Galaxy S10, Samsung Galaxy S20, Samsung Galaxy S21, and others support the Wi-Fi calling feature.

Recommended: Fix WiFi Keeps Turning Off Automatically on Android

We hope that our doc on Wi-Fi calling error ER01 invalid certificate was helpful and guided you well about the causes and different methods that can help you fix this issue. Do let us know about your thoughts, queries, or suggestions by leaving your valuable comments below.

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