We have just added a new service to T2A which compares your telephone numbers against both the Telephone Preference Service (TPS) register and Corporate Telephone Preference Service (CTPS) register. From our personal experience dealing with several clients we have found that a telephone number is occasionally registered on the incorrect list e.g. a business set up by a self employed individual may only be registered on the TPS register therefore only checking against the CTPS register would incorrectly say they are ok to call. The combined TPS and CTPS service cost 0.13 credits per use which works out as £1.95 per thousand numbers on our biggest credit package (1.5p per credit).