Can an employer legally defer business expenses to employee?
If they expect you be able to access the systems from home then they should pay for at least a portion of the cost. if they expect you to make business calls from home then same again they should pay for them. If they don’t then you are perfectly within your rights to say you won’t do it. As to the business bit of the t&c’s – although it is a business purpose it is not “running” a business and thousands of people use domestic lines for access to work accounts – I would not worry about it. I would worry more that the company is not going to pay you for business expenses.