This will depend on the agreement between you and your employer, and whether private calls will be covered by your employer along with business calls. If your employer pays your home telephone bills, you will be liable for tax and National Insurance on the payments unless the private use of the telephone is regarded as insignificant.
The amount of this benefit in kind will be calculated on the total payments made by your employer, less any amounts to cover business calls. The cost of line rental will be ignored.
Alternatively, if your employer has the contract for your home telephone, the benefit in kind will be calculated on the cost of the line rental as well as calls. The cost of business calls is still deducted from this to arrive at the amount chargeable.
However, if as an employee you have a definitive need for a telephone to be provided and your employer makes sure that private calls are kept to a minimum, HM Revenue and Customs may accept that as long as the private calls are minimal in comparison to the overall cost, no benefit in kind arises.
Similarly if your employer provides you with internet access in your home and this can be shown to be for business use or where private use is minimal, and the cost of the package is not affected by private use, no benefit in kind will arise.
Reimbursement of private calls made from your own home telephone would be considered a benefit in kind by HMRC and would be taxable. The provision of a mobile telephone is not regarded by HMRC as a taxable benefit even where your employer pays the cost of private calls and line rental.