There have been reports of scam calls coming from the Liberia +231 prefix, writes.
The calls are part of a 'Premium CallBack' scam.
Members of the public get a missed call from an unknown number starting with the international code +231.
The Liberia calls come in at odd hours, including late night or the middle of the day.
The scam hopes that you will call back out of sheer habit or curiosity.
Tom Butler, public affairs manager with Comreg, says there is an easy way to avoid being scammed.
He said: "So when the number comes up, if you don't recognise the number let it ring out. If it rings out after one or two rings it's most probably a scam call.
"And if it doesn't leave a message for you to ring back, do not phone unless there is a genuine reason to ring the number back, don't ring it back."
These calls mostly come in at odd times to make you feel you truly missed an important call.
In reality, the calls never last for more than two rings.
Readers who have contacted us have reported similar calls coming from countries including Austria (+43), Comoros Islands (+269), Morocco (+212), Ghana (+233), Chad (+235), Canada (+1) and Ivory Coast (+225).
Any person who calls the number back will instantly be charged a premium rate for the phone call.
The scammers often have a false 'operator' playing a message along the lines of: "Hello, you have reached the operator. Please hold."
Here, the scammers are attempting to keep you on the line for as long as possible.
Those caught by the scam may see their credit has been used up, or see a large spike in their next phone bill.