I myself have 3 rentals and have found that claiming cell phone and internet against them has *ZERO* impact on my tax liability. In other words, I'm advising you to not waste your time. Besides, home office expenses for folks like us with residential rental real estate is not allowed anyway. Only if you are a real estate professional can such expenses come into play. But even then most likely, it still has zero impact on your tax liability since it is *VERY* uncommon for residential rental real estate to show a taxable gain each year - especially if you have a mortgage on the property(s).
