For personal use:
You can't deduct the cost of a phone.
You can't include the sales tax for a trailer in your sales tax deduction, because it is not a motor vehicle.
If used in business:
You can deduct the portion of your monthly phone bill that you can allocate to business use. If you use your personal phone for business, you must have some way of determining the percentage of business use based on reliable records that you can show the IRS if audited. You may also be able to list the phone as a business asset and depreciate a percentage of the cost on the same allocation.
If you purchase a trailer for use in business, the sales tax is included in the cost of the trailer. You list it as a business asset and take depreciation based on that purchase price. (For a small utility trailer under $2500, you may qualify to take all the depreciation in the first year, but you still have to list it as an asset, not an expense, and let Turbotax tell you if you are eligible for one of the special methods of deducting the cost.)
