Your goal in the initial phone call is to determine if there is enough of a match to spend time showing and looking at the space.
You should have a clear idea of what you MUST have in a housemate and living situation. What you must have is very different from what you would like to have. In the phone conversation you can find out if the “must haves” are met by the space. If not, there is no reason to continue the conversation.
Some examples of “Must Haves” might be space for pets or no pets, space for visiting offspring, or other important people in your life, bathroom access, or convenient public transportation. For years, I had a must have of “no TV”. That made it much easier to find suitable housemates.
The point here is that your “Must Haves” can simplify the time you spend looking for a housemate.