Crossed lines

My client operates his business through a limited company of which he is the sole employee director and shareholder.

He has a mobile phone the contract for which is in his own name but which is used for business purposes.

The monthly charge for the phone is paid by the company but the HMRC inspector is now seeking to disallow the service charge – which he equates to a rental charge for the phone – while allowing a proportion of the call costs. Is this correct?

I know that in times gone by the Inland Revenue disallowed the rental element of home telephone lines on the basis that all homes had a telephone anyway so this was private but I had it in mind that there had been a recent change of practice here.

Am I correct in that regard or did that only apply...