Criminals have been using internet-based calling technology to make it look like a phone call or text is coming from a real telephone number.
Almost 45 million consumers were targeted by phone scams this summer.
Ofcom said it expected the measures to be introduced at pace as a “priority”.
So far, only one operator – TalkTalk – has implemented the new plans. Other phone networks are still exploring methods of making it work.
“We’ve been working with telecoms companies to implement technical solutions, including blocking at source, suspicious international calls that are masked by a UK number,” said Lindsey Fussell, Ofcom’s networks and communications group director.
“We expect these measures to be introduced as a priority, and at pace, to ensure customers are better protected.”
She added tackling the phone scams issue was a “complex problem” that required a coordinated effort from the police, government, other regulators and industry.