Hundreds of mobile phones and SIM cards that had been smuggled in by inmates were confiscated at a Fylde coast prison last year.
Staff at HMP Kirkham (pictured) seized more illegal phones last year than any other prison in the country.
The number of devices found, 488, was by far the highest recorded – almost 200 more than any other prison.
The figures, released following a written question raised in Parliament, follow a clampdown on contraband in prisons that has resulted in a rise in seizures nationally.
The category D open prison, which has space for up to 657 prisoners, currently houses 562 inmates.
After Kirkham, the next highest number of illegal phones seized was 290, in Altcourse.
Prisons minister Andrew Selous said: “This Government is clamping down on the use of mobile phones in prisons, and seizures have increased.
“Prisons use a comprehensive range of robust searching and security measures to detect items of contraband such intelligence-led searches, body searches, use of x-ray machines, metal detectors and CCTV surveillance cameras, as well as body orifice scanners.”
Since 2007, it has been illegal to take some items – including phones – into a prison.
Inmates caught with a mobile phone face up to two years in jail or an unlimited fine.
Kirkham councillor Liz Oades said: “With it being an open prison with a very large perimeter, it’s quite easy to throw things over the fence and into the grounds, so I can understand the difficulties of policing it.
“But whenever I visit the governor, they do check for mobile phones and take them off you.”
Across the UK, prison guards seized 7,451 phones and SIM cards last year, up from 6,756 in 2010 and 7,301 in 2012.
HMP Kirkham, based on Freckleton Road, is used to hold adult male prisoners who are almost all serving long sentences.
A report of its latest inspection, published in March, found the prison was an “impressive institution” although “use of illicit drugs was higher than we usually see in open prisons”. The presence of illegal phones in prisons is often linked to drug use.