From yesterday , UK mobile phone users can send a  text message to opt out of unsolicited sales and marketing calls under a new service from the Telephone Preference Service and regulator Ofcom. 

To register, simply text “TPS” and your email address to 78070. According to Ofcom, only 2.9m mobile numbers — around 3 per cent — are registered on the TPS “do not call” database, compared with 18.5m landline numbers (around 85 per cent). However, the service will not prevent spam text messages.