If you try to contact me with a phone call, you might as well send your message into outer space. You'll have better luck getting a response from aliens.
99% of incoming calls to my phone are spam. I won't pick up an unknown number unless someone has already contacted me and told me to be expecting a phone call, or it's a call from someone I already know (people I already know don't call me either).
That is to say, your mileage may vary on what counts as a "suitable medium".
Used to be that people had phones at the desk at work and a voicemail inbox. In a business situation I would expect most people to be reachable by phone.
This reminds me: when people insist on having a real phone call in an email, it could be something that they don't like to put in writing. So it's a good practice to ask what the topic of the phone call will be so that you can join it prepared.
If it indeed is something that you feel might be fishy, I further recommend the following: write a summary of what was discussed and send your summary to the people on the call as "meeting minutes -- 2026-02-11" (make this a habit, and always say "I do this routinely to remember what was agreed"). This can easily avoid you being trapped by dubious propsals or being unwittingly on the wrong side of the law.
I record my phone calls for personal records. Often I won't hear or remember details, so the recording helps.
Are there legal or other situations in which meeting minutes would be admissible in evidence, but a recording would not be? Obviously this is jurisdiction dependent.
if you make a recording, transcribe it, the delete the recording, it's probably hard to prove you made a recording. better yet with todays technology you can probably make a transcription live. i don't know if feeding he audio into a transcription tool counts as recording.
but the example was to use a recording in court. if you do that then everyone knows.
Samsung S24 Ultra with the stock dialer. I use DW Contacts to manage my address books, but stick with the stock dialer specifically for the recording feature. I understand this is CSC dependent.