When Duo Security is implemented as the Two-Factor Authentication, there is no option to change the default "WHMCS" to the host or company name.
The means explaining hundred of times to users what WHMCS means and it related to your company. It also means that users always fails to accept the incoming push because they don't know what WHMCS means.
There have to be an option where a company uses their name just like what the default Duo System does where you can even fine-grain it down to a website name.
Please this is necessary or else folks will stick to Google Authenticator.
Thanks for suggesting this idea and for the votes. I'm pleased to advise that in version 7.0 the DuoSecurity implementation was changed to use your own Duo account. As a result the name which is now displayed to users is defined by your "Account name" setting at Duo.