Diddy's 3-Way Call Purely Personal ... Music Mogul Drank Behind Bars

10:51 AM PT -- Sources close to Sean "Diddy" Combs tell TMZ .... our story about Diddy drinking homemade alcohol in prison "is 100 percent true." Regarding the 3-way call, we're told it was purely personal with Diddy chatting with 2 family members and their discussion had nothing to do with issuing a statement to the New York Times.

Sean "Diddy" Combs hasn't been at his New Jersey prison digs for very long ... but he's already facing possible punishment for breaking the rules, according to a new report.

CBS News obtained prison documents that outline Diddy's first days at FCI Fort Dix, along with his mug shot that shows his name and inmate number. Diddy is serving a 4-year prison term after his federal conviction for transporting male escorts across state lines for the purpose of prostitution. The music mogul was transferred from Brooklyn's Metropolitan Detention Center to Fort Dix on October. 30.

According to the CBS News documents, Diddy has already run afoul of prison rules just a few days into his incarceration at Fort Dix. Diddy reportedly made a three-person call to discuss issuing a statement to The New York Times ... but ended up in violation of the Bureau of Prisons rules. BOP guidelines bar inmates from adding multiple people to phone calls for fear inmates could use them to coordinate criminal activity.

During the November 3 call, Diddy reportedly spoke with an unnamed woman about getting in touch with "the digital person" about blogs. Then Diddy allegedly discussed arranging weekend visits with loved ones, recommending they bring "200 singles." Prison rules prevent visitors from coming into the facility with cash, but coins are allowed for the vending machines.

After the two were done talking visitation, the woman reportedly added a third party to the call -- an unidentified man -- in violation of prison regulations.

According to the docs ... Diddy later told prison officials that he was chatting with his female lawyer, who added his PR guy to the call to draft a statement to be sent to the NYT after he approved it. Diddy denied he was discussing blogs and provided no reason why he would want to issue a statement to the NYT.

In addition, Diddy claimed he was uninformed about the third-party phone call regulations ...  but prison officials still recommended he lose 90 days of phone privileges and 90 days of commissary privileges, according to CBS News. Prison officials filed the ruling November 4 -- CBS News says -- but it's unclear what the outcome was.

CBS News also reports Diddy is now employed as a chaplain's assistant at Fort Dix, which is considered a much better gig than other prison jobs. Typically, inmates who work in the chapel clean the office, preserve the library, and do record-keeping. It was earlier reported Diddy was working laundry duties at the facility.