SCIG01780 - Introduction and organisation: recording information: communicating by telephone
It is often very useful and quick to discuss matters over the phone. However in order to preserve confidentiality you must make sure you are speaking to the correct person. All HMRC cases are subject to rules relating to confidentiality (see SCIG10700 for further information on confidentiality) but SI cases, by their nature, are particularly sensitive. You must make a typed note of your telephone conversations as soon as possible after they end and retain any hand written notes in the file for evidential purposes should the case become contentious or get referred to CI.