Cell phones are "listed property" so the rules are slightly different. If you use it at least 50% for work and can prove it by the call log or other records, then you can list it as an asset and depreciate the percentage of cost equal to percentage of work use over 5 years. In some cases, you can take section 179 depreciation which is all at once, turbotax should offer you that option if you qualify.
But, work related expense deductions are limited by the 2% rule so even if you list it, you may not have an actual tax benefit, depending on your other tax facts.