# How to Approve Real Users and Block Fake Accounts at Sign Up with Lookup and Verify in C#

DevFeed: [How to Approve Real Users and Block Fake Accounts at Sign Up with Lookup and Verify in C#](<https://devfeed.tech/articles/how-to-approve-real-users-and-block-fake-accounts-at-sign-up-with-lookup-and-verify-in-c-16094.md>)

Original publisher: [Read original article](<https://www.twilio.com/en-us/blog/developers/tutorials/product/block-fake-accounts-lookup-verify-csharp>)

Author: Amanda Lange, Dhruv Patel, Kelley Robinson

Published: 2026-08-28T00:00:00Z

Content type: tutorial

Language: en

Sources: [Twilio Blog](<https://devfeed.tech/sources/twilio-blog.md>)

Topics: [C#](<https://devfeed.tech/topics/csharp.md>), [API](<https://devfeed.tech/topics/api.md>), [.NET 9](<https://devfeed.tech/topics/net-9.md>)

Tags: [auth](<https://devfeed.tech/tags/auth.md>), [c-sharp](<https://devfeed.tech/tags/c-sharp.md>), [developer-insights](<https://devfeed.tech/tags/developer-insights.md>), [fake-accounts](<https://devfeed.tech/tags/fake-accounts.md>), [fraud](<https://devfeed.tech/tags/fraud.md>), [how-to](<https://devfeed.tech/tags/how-to.md>), [lookup](<https://devfeed.tech/tags/lookup.md>), [onboarding](<https://devfeed.tech/tags/onboarding.md>), [sign-up](<https://devfeed.tech/tags/sign-up.md>), [verification](<https://devfeed.tech/tags/verification.md>), [verify](<https://devfeed.tech/tags/verify.md>)

## AI overview

This tutorial shows C# developers how to combine Twilio Lookup and Twilio Verify to screen phone numbers during sign-up, verify identity, and block fake accounts. It covers line-type, reachability, identity-match, and phone-possession checks.

## Source excerpt

How to Approve Real Users and Block Fake Accounts at Sign Up with Lookup and Verify in C Sharp