RAF veteran Graham Moore, 66, admitted to three counts of downloading the illegal images at a previous hearing.
He was caught after police raided his home, in Pauls Moss Court, Whitchurch, on March 29 last year.
Prosecuting barrister Mr John Oates said the phone contained one image of category A the most serious type, two of category B and nine of category C.
He told told Shrewsbury Crown Court that Moore was previously jailed for six years for sexual offences against children in 1992.
Mr Oates said: “The police went to his home on March 29, 2018 with a warrant. They entered the premises and a search was carried out. He denied having any indecent photos.
"His laptop was checked and found to be negative.
"Subsequently they checked his mobile phones. One had 12 images of children.
"When his search history was checked, the officers found material relating to activity that he was jailed for. He was interviewed and arrested, but he refused to answer any questions.”
Mitigating barrister Mr Andrew Holland said: “He fully concedes every part of the prosecution case. He accepts that these searches were put in by himself.”
The court previously heard that the defendant suffered post-traumatic stress disorder after a plane crash in Belize more than 40 years ago.
He was sentenced to a 12-month jail term, suspended for two years.
He must attend up to 30 rehabilitation activity days and was ordered to pay £240 costs within 28 days.
Moore was made subject to an interim sexual harm prevention order restricting his use of the internet and notify the police of any change in address for 10 years.