The best thing to do would be to get the rates from Verizon of what they would charge you if you only had phone service or only had internet service. You could then use those figures to determine the percentage of the bill that applies to the internet.
As an example -- if they told you the charges for phone service alone were $40 per month and the charges for internet services alone were $60 per month, then you could assume that 60% of your bill applied to internet. Your package deal of phone and internet combined is likely lower than the separate charges would be for those services but it would be safe to use those same percentages.
As far as taxes and fees, I would just take your whole bill and apply the percentages based on the information they give you for pricing the services separately.
In cases like this where the charges are not always clear, the IRS just requires that you use a reasonable method for determining the charges that apply, and this would be considered a reasonable method.
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Thank you crunchy