Frequently Asked Questions

Have questions about UNDO? We got you covered! Explore the frequently asked questions by our community

  • How do I become an UNDO customer?

    Very simple! You can download our app and complete an order. You can also do this on our website if you login.

    You choose your subscription and add-ons and complete the order.

    And if you order an eSIM it will be activated already within the hour and you’ll be able to get started already immediately!

  • How can I transfer my actual phone number from another operator to UNDO?

    During your order you can fill out the details of your old operator and we’ll deal with the transfer of your number to UNDO. Make sure to fill in all fields and all information 100% correctly for a smooth number transfer.

  • Which network does UNDO use?

    UNDO uses the Orange network. There is nothing more annoying than a video that won’t load. Our SIM cards are equipped for 5G, both the eSIM and the traditional SIM card. Therefore, our users can rely on a strong and fast network in all regions.

  • How many SIM cards can I order?

    You can order up to 7 SIM cards as a private user and up to 25 SIM cards as a business.

  • How to buy an eSIM?

    During the onboarding you can simply choose if you want a eSIM or a physical normal SIM.

  • Why choose an eSIM?

    An eSIM is a digital SIM card, the successor to a traditional physical SIM card. At UNDO, you don’t pay any costs for this type of SIM card. Thanks to an eSIM, you can start surfing, calling and texting within minutes after you ordered. Note: not all phones support an eSIM. Devices that do, also offer room for a physical SIM card. With such a Dual SIM device, you kill two birds with one stone. You can use two numbers, and therefore two subscriptions. Compared to a traditional physical SIM card, an eSIM has many advantages:

    • You can easily switch between 2 numbers if you have a Dual SIM.
    • So you decide for example which number you call with, and which number you surf with.
    • Outside the EU, you can easily use a local SIM card.
    • Smartphone lost or stolen? Then activate a new eSIM in 1-2-3 in your replacement device.
    • No need to change physical SIM cards anymore.
    • You choose a more environmentally friendly alternative.
  • How to activate an eSIM?

    Once you’ve ordered an eSIM you’ll receive an email with the installation procedure.
    Is this eSIM for another person? Then forward this email so it can be installed on his/her device.

    Follow these steps for the eSIM installation:
    – Scan the QR-code in the email with the camera of your device
    – Follow the steps and unblock your eSIM with the PIN-code in the email

    Please note that after scanning the QR-code and installing the profile you will receive a SMS once your eSIM has been activated.
    Important: DON’T delete the installed eSIM from your device because you can only install the QR-code once!

    Pay attention: if the installation with the above steps fails you can also activate it manually:
    – For Apple : go to “Settings” > “Cellular” > “Add Cellular Plan” > “Use QR-code” and complete the steps
    – For Android : 
       Go to Settings > Connections.
       Tap on SIM card manager.
       Select Add mobile plan.
       Navigate to Other ways to add plans.
       Choose Add using QR code.
       Scan the provided QR code.
       Follow on-screen prompts.

  • My eSIM is not working

    Please follow the steps below if your eSIM is not working:
    – Make sure that the eSIM is active and unlocked with the PIN code in your phone’s settings (you can find the PIN code in the email with the QR code you received for installation).
    – If you still have an (old) physical SIM card in your phone, it is best to remove it.
    – It is also best to set the eSIM as the primary SIM. If you have multiple SIM cards/eSIMs in your phone, the UNDO eSIM might be a secondary number. You need to set it as the primary SIM so that your calls/SMS/surfing will be done with the UNDO eSIM.

    After following the above steps, restart your device to establish a new network connection.
    Do you still have no network coverage with your eSIM? Then order a SIM SWAP to install a new eSIM.

  • Transferring my eSIM to another phone

    You can transfer your current eSIM to another phone by ordering a SIM SWAP in your app or in “My account” on In “My account,” under “Your plan,” go to “Manage” and then choose “SIM SWAP.” Select eSIM and follow the steps. You will receive a new QR code via email, which you can use to install your eSIM on your other phone.

  • How do I replace a normal SIM card with an eSIM? (SIM SWAP)

    You can order a SIM SWAP in your app or in “My account” on In “My account,” under “Your tariff,” go to “Manage” and then choose “SIM SWAP.” Select eSIM and follow the steps. You will receive a QR code via email, which you can use to install your eSIM.

  • How do I replace an eSIM with a normal SIM card? (SIM SWAP)

    You can order a SIM SWAP in your app or in “My account” on In “My account,” under “Your tariff,” go to “Manage” and then choose “SIM SWAP.” Select a Regular SIM and follow the steps. When you receive the SIM card at home, you can activate it in “My account.”

  • My PIN code is blocked. Where can I find my PUK code?

    If unluckely you entered 3 times a wrong PIN code, your SIM card will be blocked. This aims to protect it from unintended usage from others.
    To unblock your SIM card, you need to use your PUK code (Personal Unblocking Key). You will find this PUK code on the plastic card, which was holding your SIM card. Please keep it in a safe place and not near your handset.
    To unblock your SIM card, you just need to follow the instructions on your handset with the use of your PUK code.

  • How can I change my PIN code?

    The standard PIN code can be found on the plastic card, which was holding your SIM card. You preferably change it by a code you only know.
    How to change your PIN code? If you want for example the code “1375” as a new PIN code, you enter *04oldPIN13751375# on your phone and press the dial button. The PIN code is now changed to your new code.
    For security reasons, you better do not choose sequential numbers (1234) or same numbers (2222).

  • Can I switch off my PIN code?

    You can switch of the PIN code of your SIM card. You can do this in the settings of your handset but we advise you not to do so for security reasons.

  • How can I change the language of my SIM card?

    You can change the language of your simcard in the app or in “My account” on

  • How can I find my SIM card number?

    • On the back of your current SIM card
    • In your smartphone settings:
    • For iOS
    1. Go to ‘Settings’ > ‘General’ > ‘About’
    2. Scroll down to ‘ICCID’.
    3. Touch and hold to copy the number.
    • For Android:
    1. Go to ‘Settings’
    2. Scroll down to ‘About phone’ or ‘About device’ depending on your phone model.
    3. Choose ‘Status’ and tap ‘ICCID’.
    4. Tap and hold to copy the number to your clipboard.
  • What is an IMEI number?

    The IMEI number (International Mobile Equipment Identity) is the identification number of your handset.

  • Where can I find the IMEI number?

    Call the *#06# code. The IMEI number will appear on your handset.
    On some older handsets, the IMEI number can be found under the battery of the handset or on the original box of the handset.

  • My phone has been stolen/My SIM card lost

    Please contact our Support to block your number.
    And you can then order a SIM SWAP in your app or in “My account” on

  • What type of format of SIM card do I need?

    There are three types of SIM card sizes:
    – The standard SIM card (dimensions: 25 x 15 mm);
    – The micro SIM card (introduced by the iPhone 4, but now commonly used in most smartphones);
    – The nano SIM card (used in some smartphones such as the iPhone 6s, iPhone SE, Samsung S6, Samsung S7, and iPads).

    At UNDO, we provide a multi-format SIM card as standard. This card contains all SIM card sizes in one convenient format. You only need to punch out the desired size from the card. If you accidentally choose the wrong size, don’t worry, you can use the remaining sizes as an ‘adapter’: click the smaller size back into the larger form and insert it into your device.

  • What is an out of bundle limit?

    You can choose how much you can spend outside of your monthly subscription and addons. If you reach the selected amount, your out of bundle consumption will be blocked till the end of the month.

  • How do I change the out of bundle limit?

    You can change it in the app or in “My account” on

  • Useful numbers (1987 + 1989)

    Voice Mail:

    In Belgium, call the free number 1987.

    From abroad, call +32490461997 at the standard roaming price.

    Customer Service:
    If you have questions, you can reach one of our agents every weekday from 8AM to 6PM by calling 1989 with your mobile or  +32490461999 from any other phone.

  • How can I activate my Voicemail?

    The voicemail service works like a classic voice recording system. This service is free of charge. To configure your voicemail, you just need to call 1987 and configure a welcome message.
    The standard welcome message looks as follow: “This is the voicemail of …” followed by your mobile number.
    To personalize your voicemail, please record a personal message and save it.

  • Voicemail deactivation or reactivation

    To deactivate your voicemail, you just need to call 1987 (with your handset) and select option 4 “to deactivate or reactivate your voicemail.” By doing this, your voicemail will be directly deactivated.
    To reactivate your voicemail, you just need to call 1987 (with your handset) and select option 4 “to deactivate or reactivate your voicemail.”

  • Listen to your Voicemail

    You will receive a SMS each time there is a new message on your voicemail. 
    To listen to your messages, you just need to call 1987 (with your handset). 
    If you are abroad, you need to call +32490461997 to listen to your messages.

  • How to change the language of my Voicemail?

    To change the language of your voicemail, you need to change the language of your SIM card (see FAQ: “Change the language of my SIM card”).

  • How do I change the pick-up speed of my Voicemail?

    Choose how many seconds you allow the phone to ring before the voicemail picks up. The standard time is set for 20 seconds but you can change this duration: if you want your voicemail to pick up after 5 seconds you have to type **61*+32490468787**5# on your phone keyboard and confirm with the dial button. Instead of 5 seconds you can also choose between 10, 15, 20, 25 or 30 seconds. If you want to do this you have to change the 5 in the instruction with the number of seconds you want.

  • How do I forward my call to another number?

    You can choose to forward your calls to any fix or mobile phone number. You can even choose when the calls will be forwarded:

    If you’re on the line (you are having a call):
    – Activate:  Enter **67*number to forward to# on your handset and press the dial button. Example: **67*+32486123456#
    – Deactivate: Enter #67# on your phone and press the dial button.

    • If your handset doesn’t receive any signal (your handset is switched off or you don’t have any network coverage):
    – Activate:  Enter **62*number to forward to# on your handset and press the dial button. Example: **62*+32486123456#
    – Deactivate: Enter #62# on your phone and press the dial button.

    • If you can’t answer to a call:
    – Activate:  Enter **61*number to forward to# on your handset and press the dial button. Example: **61*+32486123456#
    – Deactivate: Enter #61# on your phone and press the dial button.

    • If you wish to forward all types of calls: 
    – Activate:  Enter **21*number to forward to# on your handset and press the dial button. Example: **21*+32486123456#
    – Deactivate: Enter #21# on your phone and press the dial button.

    To deactivate all your call forwarding commands, you just need to enter ##002#  on your phone and press the dial button.

  • How are call forwardings being charged?

    You will be charged for diverted calls at the same rate as a call you would do yourself. 

  • I’m getting undesired malicious calls

    If you receive anonymous malicious calls or SMS messages on your handset and you want to know the identity of the suspected person of these calls or SMS messages, you can submit a complaint to the mediation service. You can do this here.

  • I can’t configure a personal hotspot

    If you have an iPhone, you must also enter a separate APN with personal access point (hotspot) information, please enter this information and follow these steps in your iPhone:
    • Go to settings
    • Access the mobile network
    • Access the mobile data network
    And that’s what the 3 settings are for:
    • APN for ” Mobile Internet “
    • APN for ” MMS “
    • APN for ” Personal Hotspot “
    In this 3rd step ” APN for Personal hotspot “, you must make sure that this information is entered correctly:
    • APN:

  • How much characters an SMS can it contain?

    An SMS can contain up to 160 characters. If you message exceeds the 160 characters, it will be counted as a second SMS (of 160 characters as well). If your message exceeds 320 characters, it will be counted as a third SMS etc, per each 160 characters.

  • I can’t send SMS messages

    Please verify if the SMS central (SMSC – Service Center) is correctly configured in the parameters of your handset. 
    This number needs always to be +32495002530.

  • Does UNDO has a 5G network?

    Sure, our network Orange invests more than ever in the network so you can stay connected with your friends and with your favorite content. 

    Orange is completely renewing the 4G-netwerk and is gradually rolling out 5G.

  • Does UNDO support VoLTE & VoWIFI?

    VoLTE stands for Voice over LTE, i.e. 4G calling. 
    You can automatically benefit from VoLTE technology if you have a compatible smartphone.

    Calls via WiFi
    Do you sometimes experience weaker mobile (4G/5G) network coverage, but are connected to Wi-Fi? Good news: you can also make calls via the Wi-Fi network (Voice over WiFi) when the mobile network coverage at your home is insufficient. Therefore, having good Wi-Fi coverage is important to ensure optimal call quality over Wi-Fi.

  • How can I stop third party services?

    If you want to avoid receiving expensive SMS’es or/and calls and therefore your expenses are mounting up due to this excessive use of third party services, you can block these services by following the instructions below:
    – Send STOP by SMS to the short number of the third party. This will unsubscribe you from the service in question.

  • How do I suspend my number temporarily?

    Please contact

  • How can I stop my subscription/contract?

    Please fill out the UNDO Withdrawal form and send it to We will then deactivate your number and cancel your subscription. However, you will still receive a final invoice for that month.

  • How can I delete my account?

    To access the section for Account deletion on the App, go to “My account” on and log in through the authentication process. Click on More > Settings > Account settings > Delete account and proceed to confirm the choice. This way you will immediately provide the system with the input for deleting your Account. 

    More information on account deletion can be found here.

  • What is the difference between “International” and “Roaming” calls?

    – International calls are used to call from Belgium to another country.
    – The term “Roaming” is used to make and receive calls from abroad.

  • Calling from abroad (Roaming)

    You can call and send SMS messages from abroad to all other countries.
    For an overview of countries and prices, please visit
    To call someone from abroad, you must add the + or 00 sign in front of the country prefix. Do not forget to remove the first 0 from the phone number. For example: you want to reach the Belgian number 0487030405 from abroad. You must dial the following number: +32487030405 or 0032487030405.

  • I cannot call, send an SMS or surf abroad

    – When you are abroad, your handset is automatically connected to a local operator (the name of the local operator appears on the screen of your handset). If you can not call, send an SMS or surf with this operator, go to the settings of your handset and manually select another operator with whom you try.
    – Just try restarting your mobile.
    – To call someone from abroad, add the sign + or 00 in front of the country prefix. Do not forget to remove the first 0 from the phone number. For example: you want to reach the Belgian number 0487030405 from abroad. You must dial the following number: +32487030405 or 0032487030405.

  • Calling to abroad (International)

    You can call and send SMS messages from Belgium to all countries.
    For an overview of countries and prices, please visit
    Do not forget to add the prefix of the country of your correspondent preceded by the sign + or 00 and without the first 0 of the number. 

    For example: you want to call the number 0402811215 in the Netherlands. You must dial +31402811215 or 0031402811215.

  • When does my invoice start?

    Your subscription starts on the day your number was activated. You’ll receive your 1st invoice at the start of the next month on which you’ll be charged partially for this month (from the day of your SIM card activation) as well as for the next month. 

  • How do I receive my invoices?

    You will receive your invoices digitally via email.

  • What happens if I don’t pay or forget to pay?

    Once you receive the invoice, you have 15 days before it expires. After this date, you will receive several payment reminders via SMS and email. If you still haven’t paid by then, your number will be deactivated.

  • How can I pay my invoices?

    You can pay your invoice through online payment or via direct debit. You can do this in the app or in My Account.

  • What are my CO² emissions?

    Your CO2 emissions are a result of using your smartphone on a daily basis.  Smartphones work on various rare earth minerals such as Gold, Cobalt, Lithium, silver, and silicon. The mining of these components releases carbon into the atmosphere. Similarly, the manufacturing of the smartphone also causes emissions. As a user of smartphones, we also rely on our 4G/5G networks to make calls, surf the internet, use various applications, and occasionally send texts. These networks consume electricity to power up and function. Electricity often comes from non-renewable sources and causes emissions as well. Similarly, our phones need to be charged which again consumes electricity and causes emissions. All these sources combined lead to CO2 emissions that can be attributed to us as users.

  • What are my CO² compensations?

    As an UNDO user, you have the chance to contribute to the fight against climate change. Planting trees is surely one simplest ways of helping and having a direct impact. That is why each new UNDO user plants one tree upon joining by default in the UNDO Forest – a natural carbon sink. But that is not all, every UNDO user can also support emerging carbon removal technologies such as Biochaar, CCS, and Enhanced Weathering via UNDO Removal. Your monthly calculated emissions can be neutralized by assigning the same or greater number of KGs across one or more removal projects of your choosing.

  • How are my emissions calculated?

    The overall emissions displayed include the following:

    (1) DEVICE – UNDO computes the emissions produced during the manufacturing of your device, taking into account whether your device is new or used. The data is gathered from environmental product reports issued by manufacturers like Apple, Huawei, and Fairphone.

    (2) BATTERY CHARGING – UNDO estimates your daily power consumption and resulting emissions based on how much time your device spends under charge.

    (3) TELECOM USAGE – The energy consumed by the network to provide you with services such as calls, text messages, and data is calculated by UNDO according to your number of calls, SMS, and GBs used.

    (4) ONBOARDING & ACTIVATION – UNDO also factors in the one-time emissions resulting from the ordering and activation of your UNDO SIM card.

  • What are my carbon KGs?

    Just like GBs each UNDO subscription includes a certain amount KGs. Consider these as your personal emission credit that can be used to compensate your monthly emissions resulting from your smartphone use. You can find these KGs and projects in UNDO removal section Just log in to the application, assign KGs to the project you like and hit Compensate! This represents your support for the choice of projects and helps in connecting users directly to Projects at the tap of a screen.

    In case your emissions are higher than the available KGs you can purchase extra KGs. You can find these add-ons by tapping on ‘SHOW ME’ in ‘Your Tariff’ section via the mobile app or web. Your KGs that remain after compensation will be carried over and added to your available quota next month.

  • What is UNDO Removal?

    UNDO Removal aims at connecting the UNDO community to literally carbon removal technologies! In an attempt to balance the amount of carbon released due to human activity, these technologies ensure the removal of atmospheric carbon and long-term storage for over 100 years in different forms such as demolished concrete, or underground sequestration! One of the most critical challenges of the present day faced by such technology-driven projects is the high cost of project execution, which can be lowered by applying the principle of economies of scale. UNDO procures high-quality, certified REMOVAL credits from individual project developers across the globe. Projects are verified by independent 3rd party agencies and follow internationally recognized benchmarks and reporting standards such as Gold standard, Puro earth, and Verra. For users, UNDO removal is a way to choose projects of their choice and be carbon-neutral by compensating their emissions every month. You can use your CO2 KGs pre-included in your monthy subscription

  • What is UNDO Forest?

    UNDO Forest is a project that aims to create a natural carbon sink that will absorb and store carbon below the ground in soil. It’s 100% owned by UNDO. The project is being developed in the Democratic Republic of CONGO, near the town of Kinshasa. We work in collaboration with our partner IBI Village, which helps us with on-ground activities. The project aims to plant 25.000 trees in its 1st phase. The concept of agro farming is applied that ensure maximum utilization of the land and turn a dry Savannah into a habitat filled with Acacia, Corn, and Manioc. Every new subscription guarantees planting 1 tree but that is not it. Under the project, users can also support additional social initiatives by adding UNDO forest add-ons to their monthly subscriptions. This way the community not only helps the planet but also helps out the local population by providing employment, and aid, much like the UN sustainable goals.

    UNDO provides regular updates about the progress of the project and on ground activities via photos, videos, or even interviews of locals via our social media channels. Follow UNDO on Facebook, Instagram, Tiktok to stay updated.

  • What are UNDO Forest add ons?

    UNDO forest add-ons are initiatives that are aimed at improving the lives of the locals and helping quicken the plating of trees in our UNDO forest.  The projects are actually picked from the list of wishes that was put together by the locals that live nearby and help us in maintaining the trees, planting new ones or even building firewalls to protect our precious forest from burning down in natural forest fires during the dry season. These initiatives directly help improve the quality of life of the locals in the form of planting more trees, providing medical aid for local families, educational support for their children, or even buying consumable farming tools, or preserving important members of the biodiversity such as bees!

    You can find these add-ons by tapping on ‘SHOW ME’ in ‘Your Tariff’ section via the mobile app or web.