The join PKB URL is environment specific and should be tailored to whether you are in test or production. The teamcode part of the URL is optional. The teamcode is used to switch the default PKB logo to a customer specific logo on the join PKB webpage. The teamcode value is supplied from PKB.
The join PKB URL supports different query parameters that can be set to allow fields to be pre-populated on the join PKB webpage.
Examples
Sandbox (including example teamcode): http://sandbox.patientsknowbest.com/join/mchft_prt_code?t1=invitationCode&t2=token&e=email
Sandbox: http://sandbox.patientsknowbest.com/join/?t1=invitationCode&t2=token&e=email
Production: http://joinpkb.com/?t1=invitationCode&t2=token&e=email