I noticed that the Okta Voice Call Authentication callback option for MFA was not working for my Cell phone number. It was working around 5-6 months ago. After troubleshooting this, I found that T-Mobile has a feature to block “Scam Likely” calls. Okta calls were coming into my phone showing up as Spam calls so T-Mobile was blocking it up stream. I don’t know how this feature got turned on but it was. I’m talking about T-Mobile here but other ISP’s will have a similar feature. If you have users who are not receiving their MFA callback, this might be something to look into. I’m hoping Okta will resolve this issue where their calls are coming in as Spam.
If you go to the link below, you can read about the feature: