Thanks for your question.
Quite the opposite, Ringotel Shell completely integrates with your FreePBX. It extends capabilities of your FreePBX extensions and each user created in Shell would have the same SIP credentials as your FreePBX extension. You can have as many of them as you need and Shell’s users and FreePBX users can communicate the same way as before. You can think of it as a soft phone but with more capabilities.