A homesick killer was found with a phone hidden up his backside.
Talos Miller, 29, who has spent a decade behind bars for the manslaughter of David Stimpson in Nottingham, claimed he only wanted to call his mother.
He had to be wrestled to the floor by officers when they detected a phone in his cell at Parc Prison in Bridgend,.
Cardiff Crown Court heard the mobile was lodged in his backside and he had a SIM card in his pocket.
David Pugh, prosecuting said: "The phone was not used for any criminal activity.
"He had called his mother in Manchester because it was cheaper than the prison phones."
His defence barrister Jonathan Webb said: "His strongest mitigation is his guilty plea."
Judge Jeremy Jenkins added 16 months to Miller's already lengthy sentence for the phone offence.
The judge said: "Mobile phones in prison is a growing problem - especially at Parc - so much so that they now have to refer incidences of mobile phones to the police."
Miller has 23 previous convictions for 65 offences, but was given an indeterminate sentence in 2008 after he left Mr Stimpson to die when he punched and robbed the 39-year-old.
His victim was found in a pool of blood by police and died of a serious brain injury.