You must determine what percentage of the time you use your cell phone and internet for business related purposes. Then you will deduct the business portion of the bill only. Please view the Turbo Tax FAQ below for instructions on figuring the business percentage of use.
https://turbotax.intuit.com/tax-tools/tax-tips/Self-Employment-Taxes/Video--Self-Employment-Tax-Dedu...
https://turbotax.intuit.com/tax-tools/tax-tips/Tax-Deductions-and-Credits/Mobile-Phones--Internet-an...