Any barrier to logging in to your portal makes users more likely to abandon self-service and contact you directly.
Don't make users register for a separate DeskPRO account. With the Google+ app, users can log in with their existing account details.
If your organization uses Google Apps, you can limit Google login to accounts with your Google Apps domain.
Because agent and user policies are separate, you can sign in your agents through Google Apps, while still letting users log in with any Google account.
DeskPRO's flexible authentication options enable you to offer multiple login types.
You can use Google+/Google Apps sign-in exclusively, or offer it as a convenient alternative to a DeskPRO account, alongside any of 20+ other supported authentication types.