PIP telephone assessment audio recording

Hi,
I am a newbie who thought they had just submitted a question but I can't see it under my topics or anywhere else so I thought I should try again.
I have a telephone assessment due on Wednesday re a PIP review.
I thought I had read somewhere that I had to give IAS at least 3 days notice of my intention to record the interview so I phoned them yesterday. The lady I spoke to was happy for me to do this and noted it. She even said that it would save them having to do it. She did say that I should also inform the assessor at the beginning of the interview as well.
However, I have subsequently read in your PIP Guide that you advise everyone to ask for the assessment to be recorded from their end. I was also concerned to just read, on here, though that someone who requested their telephone interview to be recorded for them was moved to a video assessment (I guess so that it wouldn't have to be recorded for them)!
In conclusion, my question is "Should I ask the IAS to record the telephone interview as well as myself + do I legally need to inform the assessor at the beginning of the call as well, since I have already given notice"
Thank you, Janine xx