While this allegation has not been confirmed, an SB Nation story details that Eric Edholm of Pro Football Weekly reports that at least six player agents say their clients have been contacted by NFL teams, including the Baltimore Ravens. This of course, is in direct violations of NFL Lockout rules and could land those teams in a boatload of trouble if true.
The reports lists one player that the Ravens, along with the Cincinnati Bengals and Miami Dolphins, that was contacted after the recently completed 2011 NFL Draft. The Ravens were contacted for a response to this allegation and have not commented according to the PFW story. At this time, the NFL has said they are looking into the reports but there is nothing to warrant an investigation until further details are known.
While if the Ravens were tampering with the lockout rules would surprise me, it certainly wouldn't shock me if most, if not all of the teams have made some sort of contact with players, either before the lockout or at least during the few moments the lockout was lifted at the beginning of the draft last month.