If you are being provided with a Traffic Service and are, or elect to descend below the MSA, then a Terrain alert is given along the lines of "taking your own terrain clearance"
"Terrain
Subject to ATS surveillance system coverage, Traffic Service may be provided below ATC unit terrain safe levels; however, pilots remain responsible for terrain clearance at all times. Other than when following a notified instrument flight procedure, a pilot requesting to descend below the ATC unit terrain safe level shall be reminded that he remains responsible for terrain clearance."