h1b tranfer without stamping and payslips from employer A to B?

Hi,

My h1b has been approved on june 20th 2013 for the quota of 2014. Currently im in India.

My employer is not responding when im asking for i797? He is not able to arrange client letter for stamping.

Can I transfer my h1b to new employer without stamping and without payslips from current employer?

Do we need client letter for stamping?

Thanks,

Eximmi.