Daniel Kelley, 19, submitted his plea at London's Old Bailey this afternoon.
Earlier today, a 17-year-old who admitted to hacking offences related to the 2015 data breach was handed a 12-month rehabilitation order and had his iPhone and PC hard drive confiscated.
The teenager, who cannot be named, pleaded guilty to seven charges under the Computer Misuse Act at Norwich Youth Court last month. He admitted he was “showing off to his mates” when he posted details of his hacking online - in a Skype conversation with a friend after the event, the young man bragged he “had done enough to go to prison” the court heard.
The 2015 hack affected up to 157,000 TalkTalk customers and led to the telecoms firm's share price tanking. The group was also slapped with a record fine of £400,000 by the Information Commissioner's office for failing to prevent the cyber attack.
At the beginning of this year, TalkTalk said the incident had cost it as much as £60m due to a combination of interruption to trade and IT, incident response and consultancy costs associated with the attack.
In the aftermath of the data breach, TalkTalk boss Dido Harding gave up her bonus, instead donating the £220,000 to charity. In addition, the remuneration committee said it had decided to cut exec directors' bonuses to 40 per cent of base pay, rather than the previously expected 62.5 per cent.