This browser is no longer supported.
Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support.
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(12.8, 63%, 11%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3ELE%3C/text%3E%3C/svg%3E)
Our client has a persistent problem - one of their Azure AD B2C users is not receiving any of the SMS messages used in MFA.
Is there any way we can troubleshoot this further besides checking the user's audit logs in the B2C tenant? The logs show the SMS events as successful and the phone number related to the events is correct. Do we need to subscribe to a technical support plan and create an Azure Support Request if we wanted to get to the bottom of where in the delivery chain the message fails?
The user might obviously have the sending number blocked for whatever reason, but we can't realiably confirm that one way or the other.
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(278.4, 45%, 36%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EAV%3C/text%3E%3C/svg%3E)
Hi @Laine Eetu
Thank you for reaching Microsoft Q&A Forum!
May I know are you using the custom policy if yes can you please check your policy and see is there any changes Define a one-time password technical profile in an Azure AD B2C custom policy
Hi @Laine Eetu
We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.
It turns out the number was blocked on the recipient's end.
Can you add a different phone for MFA and see if that one gets the text? I suspect its blocked on the recipients end, yea.
We can't really - we've configured it so they need to confirm their e-mail first on their first time sign in and they haven't been able to complete the first time sign in process so I can't just change the phone number in the B2C authentication methods and try with a different one as I can't complete the e-mail step without access to their e-mail, which I don't have.
I would presume it is somehow blocked on their end yes, I was just wondering if there is any way to confirm this via Azure/Microsoft.
Hi @Laine Eetu
I'm glad that you were able to resolve your issue and thank you for posting your solution so that others experiencing the same thing can easily reference this! Since the Microsoft Q&A community has a policy that "The question author cannot accept their own answer. They can only accept answers by others ", I'll repost your solution in case you'd like to "Accept " the answer.
Issue:
Troubleshoot end user not receiving Azure AD B2C MFA SMS
Solution:
The issue happens because the number was blocked from recipient's end
If you have any other questions or are still running into more issues, please let me know. Thank you again for your time and patience throughout this issue.
Please remember to "Accept Answer" if any answer/reply helped, so that others in the community facing similar issues can easily find the solution.