Today, I will explain how to leverage an hidden gem feature from Teams: Guest user.
Whether you invite your external customers as a guest in your tenant or not, using Ticketing App will help you track all your customers requests.
By giving them access to your Ticketing instance, it will provide direct communication with the support team and real time notification, which in return will speed-up the ticket resolution.
You can invite users outside of your organization as a Guest in your Tenant following below Microsoft guide.
This might need some configuration from your Teams Administrator.
Once you have invited your guests in your tenant, they can directly raise request on the Ticketing instance you have created, no additional configuration required.