We too get all of the above types of calls. We get calls at all times of the day and into the evening & regularly get a pre-recorded message between 11.30am and 1.30pm.
Of all of the calls the pre-recorded ones are worse. If you hang up it doesn't disconnect until the message has completed. Pick the phone back up and the voice is still going.
Several times customers have left a message because our line has been jammed with the pre-recording playing it's way through.
One lunch time last week, a recorded message kept repeating itself and went on for 15 minutes! During that time we built up two messages.
I find it very annoying because not only is it a complete waste of time but it is definitely causing us to loose business as not everyone will leave a message.
When I am out, I often have calls diverted to my mobile. If one of these calls comes through to our land line, it's automatically diverted to my mobile and I end up paying for it's duration.
I'm not sure that registering with the TPS will make that much difference. I registered my parents two years ago and they still get regular calls from telecommunications companies and prize winner meassages. The problem being that calls from abroad cannot be stopped by the TPS and the majority of these calls do come from abroad.

Nicky