ISDN ISIHP modems disappear in RRAS in Windows 2000

Add S79=0 to all of the TA ports of the ISIHP-1S, ISIHP-2S, ISIHP-2U, ISIHP-4S, and/or ISIHP-4U by adding S79=0 to extra settings in the modem descriptors for the TA ports. This will prevent the TA from resetting the respective modem port when the modem disconnects. RRAS doesn't seem to like having the modem "disappear" for about 4 seconds after a call disconnects and so after a while RRAS gets into a bad state where all received calls to modem ports no longer function properly.