Explain the term "Collecting banker". What are his duties and responsibilities in this connection?

A crossed order cheque for Tk. 30,000 drawn on 'X' bank is collected by 'P' bank for the latter's customer in whose favour it has been indorsed by the payee. Discuss the position of the payee bank and the collecting bank :

(i) If the signature of the drawer has been forged.
(ii) If the endorsement of the payee has been forged.