Clean up link errors

Author: Rick-Anderson

aspnetcore/security/authentication/2fa.md

@@ -15,7 +15,7 @@ By [Rick Anderson](https://twitter.com/RickAndMSFT) and [Swiss-Devs](https://git
 >[!WARNING]
 > Two factor authentication (2FA) authenticator apps, using a Time-based One-time Password Algorithm (TOTP), are the industry recommended approach for 2FA. 2FA using TOTP is preferred to SMS 2FA. For more information, see [Enable QR Code generation for TOTP authenticator apps in ASP.NET Core](xref:security/authentication/identity-enable-qrcodes) for ASP.NET Core 2.0 and later.
 
-This tutorial shows how to set up two-factor authentication (2FA) using SMS. Instructions are given for [twilio](https://www.twilio.com/), but you can use any other SMS provider. We recommend you complete [Account Confirmation and Password Recovery](xref:security/authentication/accconfirm) before starting this tutorial.
+This tutorial shows how to set up two-factor authentication (2FA) using SMS. Instructions are given for [twilio](https://www.twilio.com/) and [ASPSMS](https://www.aspsms.com/asp.net/identity/core/testcredits/), but you can use any other SMS provider. We recommend you complete [Account Confirmation and Password Recovery](xref:security/authentication/accconfirm) before starting this tutorial.
 
 [View or download sample code](https://github.com/dotnet/AspNetCore.Docs/tree/main/aspnetcore/security/authentication/2fa/sample/Web2FA). [How to download](xref:index#how-to-download-a-sample).
 
@@ -25,7 +25,7 @@ Create a new ASP.NET Core web app named `Web2FA` with individual user accounts.
 
 ### Create an SMS account
 
-Create an SMS account, for example, from [twilio](https://www.twilio.com/). Record the authentication credentials (for twilio: accountSid and authToken, for ASPSMS: Userkey and Password).
+Create an SMS account, for example, from [twilio](https://www.twilio.com/) or [ASPSMS](https://www.aspsms.com/asp.net/identity/core/testcredits/). Record the authentication credentials (for twilio: accountSid and authToken, for ASPSMS: Userkey and Password).
 
 #### Figuring out SMS Provider credentials