Mobile phone users can now send a text message to opt out of nuisance calls from today.
The "text-to-register" service allows mobile users to add their number to the Telephone Preference Service (TPS) "do not call" database.
It is illegal for organisations to make unsolicited sales and marketing calls to numbers registered with the TPS unless they have a person's permission to do so.
Customers are able to sign up by texting TPS followed by their email address to the short code 78070.
This will result in a gradual reduction in unsolicited sales and marketing voice calls after a few days.
John Mitchison, head of the TPS, said: "Rogue callers operate illegally and against the interests of ordinary people.
"Texting will make it easier for people to register their mobile numbers on the TPS, which is the only official no-call list, and help us stamp out rogue callers once and for all by giving the Information Commissioner more ammunition to prosecute these cases."
Ofcom Consumer Group Director Lindsey Fussell added: "Many millions of landline customers already take advantage of the protection the TPS gives against nuisance calls, and we want to ensure it's as easy as possible for mobile users to do the same."
According to Ofcom, only 48% of people familiar with the TPS are aware that mobile numbers can be registered, compared to 88% for landline phone numbers.