James Dyer, aged 37, of HMP Five Wells, was sentenced to 18 months in prison at Reading Crown Court on Tuesday (9/7).
He was previously put on the sex offenders register for life.
Dyer pleaded guilty to engaging in sexual communication with a child, causing a child to watch/look at an image of sexual activity and breaching his Sexual Harm Protection Order.
On 28 February last year, the victim’s mother checked the victim’s phone and discovered Instagram messages of a sexual nature from Dyer.
Dyer had also sent the victim videos of himself containing sexual content and voice notes of a sexual nature.
These messages, videos and voice notes were sent to the victim between 2 February and 20 February, last year.
Dyer was already subject to a Sexual Harm Prevention Order at this time which prohibited him from communicating with a child under 16, which he breached.
He was arrested at a voluntary interview on 8 September last year, whilst already in prison.
Dyer was charged on 3 April this year and convicted on 1 May.
Investigating officer Detective Constable Jill Collett said: “James Dyer is a prolific offender and I am glad he will remain in prison for these crimes.
“Thames Valley Police will work with victims to prosecute the perpetrators of child sexual offences and protect the wider public.
“If you are a victim, or suspect some is a victim of crime, please contact Thames Valley Police.
“We have specially trained officers who will always listen and support you.
“You can contact us via our website, or by calling 101, or by visiting a police station.”