Hoe fix Authentication in Office 365

Question

Hoe fix Authentication in Office 365

Bhanu Singh 0

I purchased 12 month subscription from Curry. Curry technical person installed the office 365. licence is added to [Moderator note: Personally Identifiable Information removed]@SatyaIT.onMicrosoft.com. We thought it was added to [Moderator note: Personally Identifiable Information removed]@satyaInfotech.co.uk. We added a domain @SatyaInfotech.co.uk In [Moderator note: Personally Identifiable Information removed]@satyaInfotech.co.uk.

We have two problems

How to delete delete @SatyaInfotech.co.uk from [Moderator note: Personally Identifiable Information removed]@satyaInfotech.co.uk and add it into [Moderator note: Personally Identifiable Information removed]@SatyaIT.onMicrosoft.com
We are not able to login [Moderator note: Personally Identifiable Information removed]@satyaInfotech.co.uk to this as we have removed the Authenticator details for this from out mobile.

Please advice

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Answer 1

Dear @Bhanu Singh

I understand the situation. You have a custom domain tied to an old tenant/account, but your active 12-month subscription is on the new tenant. Additionally, you are locked out of the old account due to losing Microsoft Authenticator access.

To resolve this, you must first regain access to the old account so you can remove the domain, and then add the domain to your new tenant.

Here are the step-by-step instructions to fix both issues:
Step 1: Regain Access to the Locked Account

Because MFA (Microsoft Authenticator) was removed from your phone, you need an administrative MFA reset:

Option A: If another Global Admin exists in the old tenant

Have the other admin log in to the Microsoft Admin Center > go to Microsoft Entra Admin Center.
Go to Users > All users > Select your user account.
Click Authentication methods > Click Require re-register MFA (or revoke MFA sessions).
Log in again; you will be prompted to set up Microsoft Authenticator on your phone.

Please refer to this document: Manage user authentication methods for Microsoft Entra multifactor authentication
Option B: If this was the only Global Admin account

You must contact the Microsoft Data Protection Team by phone to verify your identity and reset MFA on the backend.
Find your local Microsoft support phone number via Customer service phone numbers - Microsoft Support directory.

Step 2: Remove Domain from Old Tenant

Once you log back into the old account:

Go to the Microsoft 365 Admin Center.
Go to Users > Active users. Change the domain extension (UPN) of all accounts using @satyaInfotech.co.uk back to the default @<tenant>.onmicrosoft.com domain.
Remove any email aliases or group addresses using @satyaInfotech.co.uk.
Go to Settings > Domains.
Select satyaInfotech.co.uk and click Remove domain.

Official Reference: Remove a domain from Microsoft 365

Step 3: Add Domain to New Tenant

Log in to the Microsoft 365 Admin Center using your SatyaIT.onmicrosoft.com admin account.
Go to Settings > Domains > Add domain.
Enter satyaInfotech.co.uk and complete the DNS TXT record verification with your domain registrar.
Go to Users > Active users, update your user's primary email address to @satyaInfotech.co.uk, and assign your 12-month Currys license.

Please complete Step 1 first, as domain removal requires active admin credentials on the original tenant. Let me know if you hit any roadblocks along the way.

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BabybooHN 3,040 Reputation points Independent Advisor

2026-08-14T03:09:16.94+00:00

Dear @Bhanu Singh

I hope you’re doing well. I just wanted to check in and see how things are going with the steps I shared earlier. If you ran into any difficulties at any point or if something is unclear, please don’t hesitate to let me know. I completely understand that these processes can sometimes be tricky, and I’m here to make it as easy as possible for you.

Feel free to share any details or questions you might have, I’m ready to listen and assist you further
Bhanu Singh 0 Reputation points

2026-08-14T12:53:40.9533333+00:00

I am trying to call Microsoft support on 0344 800 6006 Uk. but they are responding even wating for an hour

I am the only Global Administrator for our Microsoft 365 tenant. My account [Moderator note: Personally Identifiable Information removed]@satyainfotech.co.uk is completely locked out because I have lost access to my MFA/Authenticator registration. I cannot access the Microsoft 365 admin centre to raise a support ticket. I need a Tenant Recovery/Data Protection case to reset the MFA registration for the Global Administrator.”
BabybooHN 3,040 Reputation points Independent Advisor

2026-08-14T13:02:58.11+00:00

Dear @Bhanu Singh

If calling phone support hasn’t been effective and you’re getting disconnected, there is another option you can consider as a workaround to reach the right team. You can sign up for a new Microsoft 365 tenant by creating a trial subscription here: Microsoft 365 Business Plans and Pricing | Microsoft 365

Once that new tenant is created, you’ll be able to access the Microsoft 365 admin center and submit a support ticket directly from there. In the ticket, explain that you’re requesting assistance from the Data Protection Team for your original tenant, due to being locked out as the only admin with MFA issues. This method often helps bypass the automated loops because you’re able to submit the request from an authenticated admin center, even if it’s under a temporary tenant.

Note: Please remember to cancel the trial subscription once your issue is resolved to avoid any unintended charges.

Also, just to set expectations clearly and transparently, this is a user‑to‑user support forum, so I don’t have the ability to intervene directly or unlock accounts. I can only suggest additional options based on my experience and what has worked for others in the community.

I hope this information helps you take the right steps to regain access to your account. If you have any updates or additional details, please feel free to leave a comment under this post. I’ll be happy to assist further within my scope.