The regulations I referred to are not the event regulations, the organisers are bound by the Petroleum Regulations, as pit lane is effectively classed as a filling station forecourt during races.

You can stand at the edge of a filling station forecourt smoking and chatting on the phone but not within the forecourt itself, it's the same situation for pit lane.

The chances of a phone causing a problem are probably remote, but even if the organisers wanted to allow them, until such time as the law is changed their hands are tied.