O2 and EE mobile customers could face unexpected additional charges to their bill after reports of users being affected by an African phone call scam.
A number of users have reported being inundated with calls over the past few days, from numbers which appear to be from Guinea, Guyana and Botswana.
While users who have received scam calls have tried to block the number, scammers have reportedly been phoning back using a different number.
This is known as a ‘wangiri’ scam - a variation of a call back scam - which sees criminals call from an international number and then hang up, inviting users to call back and incur charges from the premium rate numbers.
Affected O2 and EE customers took to social media to vent their frustration, with users writing:
"O2 scam calls from Guinea started on my son's phone about half an hour ago. Constant calling interfering with his use of the phone. What exactly are you doing to fix this and how did they get the numbers of so many O2 customers? Can’t keep blocking different numbers all day!"
"@O2 my friend is being called 40 times a day by scam numbers in Africa. Your live chat has been entirely useless and keeps cutting her off. Fix this now."
"@O2 my daughter has now received over 60 calls from Guinea all different numbers. Reported to O2 and told to block and adjust do not disturb setting to contacts only. Calls still happening. This is a huge security breach what are you doing about it?"
"@EE it looks like the Guinea phone call spam is happening with your network too. I've had 13 missed calls from them, all from different numbers, so blocking them is pointless. Surely this a data breach? #o2spam #eespam #guineaspam"
"@EE hi! I keep getting loads of calls from Guinea and it’s very annoying, each one being a different number. What can I do to stop these?"
EE has reassured customers that the calls are not the result of a data breach (Photo: Shutterstock)
'Not a data breach'
In response to the complaints, O2 said the numbers have now been blocked and advised customers not to respond to missed calls from unknown callers.
An O2 spokesperson said, "We're aware of a scam that affected some customers who received unsolicited missed calls from international numbers.
"We blocked the numbers to prevent our customers calling them back and incurring unexpected charges.
"Our fraud and security team continues to monitor the situation and will take further steps as necessary to protect our customers.
"We recommend that customers don't respond to missed calls from unknown numbers, particularly an overseas number as they could incur charges if they call the number back."
Meanwhile, EE said only a handful of customers had reported an issue with the calls, with less than 20 affected and has not advised customers to check their accounts due to the issue not being widespread.
The mobile network also confirmed that the calls are not the result of a data breach and no customer accounts have been compromised.
A spokesperson said, "A very small number of our customers have contacted us about nuisance calls from international numbers this weekend.
"We've advised them to block the numbers and share them with us so we can investigate. Our systems haven't been compromised in any way.
"This is an industry-wide issue and as these calls come from outside the UK it makes tracing them extremely difficult - and is why Ofcom is working with the GSMA and The Internet Engineering Task Force to try to address this globally.
"We continually review our security and anti-fraud policies, technologies and procedures to try to protect our customers.
"Customers should be wary of accepting phone calls from numbers they don't recognise and don't return these calls."