Analysts have predicted that between three and four million iPhone 4S units will be sold during this weekend. Hundreds of thousands of people across the world have taken their position in long lines in front of Apple Stores and other carrier/retailer stores where the device is being sold.

However, there are concerns if everyone will get a phone on Friday as there's no clarity about the stock of iPhone 4S units. BeatWeek reported that at least one outlet has revealed that Apple has iPhone 4S inventory shortages. The outlet hasn't given further details or any evidence for the claim.

You can get your iPhone 4S in the following places: Apple Store: All Apple stores will open at 8 a.m. EST on Friday but long queues have already formed in front of most of them. However, getting an iPhone on the first day of release is a thing of pride and the prospect of standing in queues doesn't deter many eager fans.

Carrier Outlets: iPhone 4S will be available on three major national networks - AT&T, Verizon, and Sprint - making it a three-way race this time. Though pre-orders at all carriers have been sold out, you can go and get your iPhone 4S from the physical stores of the carriers.

Retailers: Radio Shack, Best Buy, Target and Sam's Club offer iPhone 4S in their stores. The better part of finding an iPhone 4S in the retail stores is that the sale is clubbed with offers and gifts.

However, in Radio Shack, only a small portion of its iPhone 4S inventory will be sold to people who didn't preorder, CNET has reported, citing a San Francisco sales associate.

Retailer Best Buy is still taking pre-orders for iPhone 4S and that means only a part of the iPhone 4S inventory will be available for customers who walk on today. Preference will be given to pre-order customers. Target has said it will start selling phones to customers who pre-ordered earlier. In Sam's Club stores, you will require to have a membership card.