It is against the law to use a mobile phone or any similar communication device[1] whilst driving or to use a mobile phone whilst supervising a learner. This includes texting or the use of internet etc. This also includes times where you 
are waiting at the side of the road or stopped at traffic lights etc. It is also very bad manners to use a phone while your pupil is paying for that time. Put your phone to silent or switch it off during all lessons. It could result in a fine and points on your licence, and points on your driving licence will have to be explained to the DSA who could revoke your licence to teach.
This may seem strange but I have seen many Driving Instructors using their phone while on lessons and driving. Some I have spoken too who argue that they have businesses to run and must answer their phone. I find considering the nature of the job
this attitude is so common. I do wonder what it would do to a business having a mobile phone conviction against them or worse still what it would do to the business if they were involved in a crash………………….
[1] The Road Vehicles (Construction and Use) (Amendment) (No. 4) Regulations 2003 (4) A device referred to in paragraphs (1)(b), (2)(b) and (3)(b) is a device, other than a two-way radio, which performs an interactive communication function by transmitting and receiving data.
