Sniffer dog's nose for mobiles at Parc Prison, Bridgend
South Wales Police are ringing the changes with Wales' first canine mobile phone detector.
Max, a springer spaniel, has been trained to pick up the scent of phones in prison, which officers say are a growing security threat.
The operational drugs dog can detect all mobile phone parts, including SIM cards and batteries.
After graduating from the force's dog training school, five-year-old Max will work at Parc Prison, Bridgend.
Max completed a two-week intensive course with prison and custody officer Gareth Kite.
Officer Kite, previously a dog handler with the RAF, said that the training had been a "challenging and eye-opening" experience.
"I was amazed at the talents Max demonstrated and how quickly he was able to pick up the scent of the mobile phones," he said.
"The course was incredibly informative and I was privileged to work alongside two very experienced instructors."
The instructors were police dog trainers Steve Sutton and David Conway, who compiled the programme.
PC Sutton said: "To Max, the phone is just like another drug scent.
"Upon detecting any phone part, the dog will scratch at the area to alert the handler.
"We're very happy with how successful Max's training has proved to be."
Parc Prison's head of security and operations, Mike Thomas, said: "Mobile phones are a growing problem and serious threat to security within UK prisons.
"I'm extremely grateful to the dog trainers at South Wales Police for their co-operation and dedication to the training of our mobile detection dog.
"All I can say is that prisoners at Parc had better watch out!"