When I signed up for a landline the customer service rep (BT) asked me if I wanted to subscribe to the TPS.
I must get 1 incoming call a week, and that's the mother-in-law.
*shudder*
Did BT charge you for that, I got an email from BT offering the service for a one off fee for a few quid which I thought was a scam.
I was already registered with the TPS which was free.