( CNN ) -- Polygamist sect leader Warren Jeffs ' phone privileges have been suspended , as investigators look into whether he preached from prison , authorities said Tuesday . The Texas Department of Criminal Justice announced last week that it had initiated an investigation into claims that Jeffs used the phone to preach to his congregation on Christmas Day . Records show that Jeffs made two phone calls on Christmas Day , said Jason Clark , a Criminal Justice Department spokesman , who declined to identify the people who lost their phone privileges with Jeffs . `` It would be a violation of the rules if the person called were to place the call on speaker phone or record the conversation . The Office of Inspector General has asked us to suspend the accounts of certain individuals on his calling list while they continue to investigate , '' said Clark . Texas inmates are allowed to call as many as 10 people who have registered with the offender phone system vendor . Calls can be up to 15 minutes in length , and offenders are limited to 240 minutes of phone time per month . All calls are recorded and monitored except those between an inmate and his attorney . Jeffs remains isolated in protective custody in the state 's Powledge Unit prison facility near Palestine , Texas . `` He has no cellmate . No prison job . And the only time he leaves it ( his cell ) is for a shower and recreation , '' Clark said . Jeffs , the leader of the Fundamentalist Church of Jesus Christ of Latter-day Saints , is serving a life-plus-20-year term in Texas for sexual assault . He was convicted in early August of the aggravated sexual assaults of a 12-year-old girl and a 15-year-old girl that Jeffs claimed were his `` spiritual wives . '' The 10,000-member church is a breakaway Mormon sect that openly practices polygamy in the twin border towns of Hildale , Utah , and Colorado City , Arizona , as well as on its Yearning For Zion ranch near Eldorado , Texas . The mainstream Mormon church renounced polygamy more than a century ago . Many sect members have disavowed Jeffs over his criminal convictions , while others are defending him and casting his conviction on sexual assault charges as an act of persecution . Last week , a long-time follower of Jeffs said he had been ex-communicated after admitting to having sex with his wife -- a violation of an order that the sect leader apparently issued from behind bars . The church member spoke on condition of anonymity because of the sensitivity of the issue . CNN 's Gary Tuchman contributed to this report .
NEW : Warren Jeffs loses his phone privileges for now . The judge in the case said he would not allow him to use a cellphone or computer without permission from the court. Texas inmates are allowed to have as many as 10 people on their call list . Jeffs is currently serving a life-plus-20-year term in Texas for sexual assault .