H1 transfer with receipt number of H1 extns

[sonika1]

Hello Immihelp,

I am in USA with H1 Visa.
My Visa is going to expire next month 15th(August 15th-2008).

My present employer applied for extension of my H1 and got the receipt number on May 22nd-2008.

If I want to transfer my H1 to another company after - August 15th-2008(after old valid I-797)- what is the procedure?

Is it possible with my receipt number?

Thanks,
Soni