I have a virtual address in the U.S. and doing an ecommerce biz on promo items. Do I need to get U.S. permit?

I have a virtual address located in the U.S. but basically I sell promotional products online. I am located outside the U.S. and because of the power of Voice over Internet Protocol or Voip service I can make a client call int the U.S. The reason for having a virtual address is for customer support and trust and that my purchase invoice from suppliers may mail me the invoices as well. Now my question is do I need to get a business permit/licenses to sell? I am actually doing a sales calls over the phone and it is a business to business transaction? Thanks.

What i mean do I need to get a US permit/license in order to sell the products? Both my suppliers and customers are from the US, so shipping is not the issue. But I am from the outside US, i make calls to customers through my VOIP line

As far as I know if you invoice your clients with your local address you shouldn't need to. The logic for me is that you generate the funds from abroad and thus have to pay only for the US Customs should you send products.

Should you declare the revenue locally check if they have a Tax Agreement with the US.

I am in the same boat there and do it exactly the same way that you described. Nobody got angry with me yet! Made official inquiries at the US IRS and they seemed to be o.k. with it. [Not too helpful people either I have to say].