Head Constable Rajkumar Singh was arrested last night by the Special Cell of Delhi Police after being called for questioning, police said.
Singh was posted at the office of the Assistant Commissioner of Police at Khajoori Khas.
Six persons were arrested on the intervening night of Wednesday and Thursday for allegedly illegally obtaining CDRs.
Assistant Sub-Inspector Gopal, Head Constable Harish and Constable Harish Kumar had been arrested along with private detectives Punit Verma, Alok Gupta and Mehraj Saifi.
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According to sources, more arrests are on the cards in this case with even some senior police officials coming under the scanner.
Four persons - Delhi Police constable Arvind Dabas and three private detectives, Anurag, Neeraj, and Nitish - had been arrested for allegedly trying to obtain Jaitley's CDR in February this year.
"The seven persons arrested are part of a second module which procured the CDRs of high-profile persons.
"The first module, headed by Dabas, was arrested for procuring Jaitley's CDR. The Dabas group was involved in procuring CDRs of some 30 people while the group arrested over the last two days accessed call details of 22 people," said a senior police official.
The matter came to light in January and led to a political furore with the Opposition accusing the government of tapping Jaitley's phone.
According to police, CDRs of 52 numbers, three of them belonging to Jaitley, were sought by the accused using the e-mail id of the Assistant Commissioner of Police (Operations), New Delhi district, on January 8, 2013.
The accused policemen would procure the CDRs of influential persons and hand them over to private detectives in return for cash and other benefits.