Letter of Authorization to Obtain Government Pricing

Hello...

I have a customer who is asking how we can provide a letter of authorization to obtain Government Pricing.  We just awarded a contract to an SDVOSB.  The Contractor needs to provide cell phones to his employees and other supplies.  Without using GSA Schedules, he would like to go to a dealer, "Verizon" for example to obtain government pricing on the phones.  I can't seem to find any authority for this ... has anyone else heard of this?  Is there a way to do it?  Attached is a sample letter they provided me.  Is there any authority that permits this?

Thank you

LOA Example.docx