TPS is great, I've been enrolled for years and despite being in the public phone directory I get zero unsolicited marketing calls. Only takes 28 days to become effective and no re-registration is required for residential lines.
From:
http://www.tpsonline.org.uk/tps/faq/:
Why do I have to wait up to 28 days for the service to become fully effective?
It is a legal requirement for telemarketers not to call a TPS subscribed number after it has been registered for 28 days. Upon registering with the TPS you should notice a gradual reduction of unsolicited sales and marketing calls after a few days but please allow 28 days for the service to become fully effective.
16. Do I need to renew my subscription with the TPS?
If you have registered a residential number or a number belonging to a sole trader or (except in Scotland) partnership, you do not need to renew. However, if you have registered a number on to the Corporate TPS belonging to a Limited company, Plc or other large organisation, you are required to renew annually
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DougM