.Hi, I work for company A and my H1B is Effective from last year. I wan't to switch to company B. Suppose the company B files H1B petition (for transfer, same process as for new one) with starting date of Nov 1 2007. If this petition is aoproved, 1. Is it mandatory to join Company B? Or can I continue working with company A ignoring new H1b approval? 2. If I must have to join Company B, shall it be immediate or is there any specific period whithin which I have to join? thanks trader