H1B Approved but don't have Acknowledgement number


My employer applied for my H1B visa and as per them it is approved now. However, as per the company policies they have not communicated any Acknowledgement/Receipt number with me (it is shared at the time of visa stamping only). I have another opportunity now with another company who wants to send me to US, is there any way I can get my approved H1B petition processed or I would need to go thorough the same process again with the new employer?

You should get the Acknowledgement/Receipt number from the primary Employer who filed H1

Is there any way to get this from USCIS. I am asking this because in a situation of resigning from my current employer I may not get any references for my H1.