The server to server authentication mechanism where in your server will pass Teamchat server an authentication token and an email id works. Teamchat server will return the user id and user token in return. This user id and token will be used to directly launch the Teamchat home screen of the user.
If you want to leverage on Teamchat OTP mechanism for authentication using your own screens, we are coming up with the APIs for registration, otp and update profile. Will let you know once they are out. Kindly go through TCAuthorizationModes.doc