A phone system can capture audio perfectly and still create a record the firm cannot lawfully or safely use. The decision to record should come first, and it has to account for where each participant is, what the conversation is about, client confidentiality, who can access the file, and how long it is kept.
This paper separates recording consent, professional confidentiality and privilege from the technical setup, and gives test plans for consent on every call type, access logging, archive recovery and preservation holds.