Martin Lewis issued urgent advice to anyone with a mobile phone.
The finance guru shared the tips during an episode of ITV's Martin Lewis Money Show Live.
Thursday's edition was dedicated to helping people reduce the cost of some common bills in the wake of soaring energy prices.
READ MORE: Martin Lewis issues urgent £1,925 warning to everybody in UK
Martin devoted the first segment of the show to how people can reduce their mobile phone bill.
The finance expert explained the price of the average 4GB phone deal has halved in the past five years and urged people to check their contract.
He said: "If you haven't sorted out or changed your mobile phone deal, you are likely paying way too much.
"My big question would be, 'are you paying over £10 a month?" If so, why?"
Martin conducted a poll with his Twitter followers and found over 30% of the people surveyed pay more than £30 a month for their mobile phone.
He continued: "If part of that is repaying a handset, fair enough. If it's because you roam a lot, then fair enough.
"Maybe if you've got poor credit and you have to be on pre-pay, but that shouldn't be too much more expensive."
Martin recommended people to switch their SIM card in order to bring down the price of their mobile phone bill.
The Money Saving Expert showed examples of cheap SIM deals starting from as low as £6 a month for a 10GB deal with Lebara.
Martin explained that lesser known provides piggyback their signal from the major four networks so people should not be worried about a drop in service.
He said: "If you want to cut your cost you can keep the same signal, but by changing to a different virtual network."
The consumer champion also said anyone who wants to switch SIM card can keep their current mobile number by texting PAC for free to 65075.
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