Abstract: A telecommunications terminal block provides service wire terminations within cells that are electrically and physically isolated from other cells in the block, and from the environment, thereby effectively preventing corrosion and shorting by eliminating electrical bridging between tip and ring service wire circuits. Cell 21 in the dielectric terminal block body 10 contains a pair of spaced-apart contact surface members 32, 35 that are forced into compression engagement upon an inserted service wire end 26 by threaded advancement of a dielectric plug 13 situated within the cell. A conduit bore 12 in the block wall directs insertion of the stripped service wire 16 between the contact members prior to plug advancement, and a gasket member 38 extending across the annular space between the plug and the cell wall, with an optional cell-filling gel 47, ensures exclusion of the environment from the cell and isolation between tip and ring circuits.