Generally, a cold call should only be for a few minutes. The only time it should go longer is if you happen to come across a prospect that we might describe as “a unicorn” and who cannot believe that you have called them because they have been looking for a solution about the very reason you are calling.
In my training and development field, this happens quite a lot when I am calling resource managers. There is nothing more exhilarating when the person on the other end of the phone says, “I do not believe this. I was just thinking about the need to run a time management training course literally 30 minutes ago. So, can you tell me about your time management courses?”
You may want to take a little bit more time in this event, but not too much. Ideally, in this situation, my goal is to set up either an in-person or zoom meeting sometime later in the week. It is highly unlikely to try to close a high ticket sale on the first call.