VOIP/PSTN

I AM CONSIDERING INSTALLING A ROCKWELL ACD INTERFACED TO THE PSTN THROUGH 2 ISDN PRI TRUNKS. I WOULD LIKE TO UTILIZE THE DESKTOP FOR THE VOICE COMPONENT INSTEAD OF USING 2500 TELCO SETS FROM ACD VOICE PORTS. I UNDERTSAND THAT DIALOGIC OR PERHAPS OTHERS HAVE CARDS THAT WILL ALLOW THE IP TO PCM CONVERSION TO TAKE PLACE. CAN ANYONE VALIDATE THIS AND IF SO, IS IT THE DIALOGIC IP LINK OR DUAL SPAN CARD? DO THESE CARDS ELIMINATE THE NEED FOR A GATEWAY SINCE THE TRUNK CONNECTION IS THROUGH THE ROCKWELL ACD SERVER? ARE DIALOGIC CARDS USED AT BOTH THE ACD SERVER AND THE DESKTOP OR ARE DIFFERENT CARDS USED AT THE 2 LOCATIONS? ANY INSIGHT IS GREATLY APPRECIATED. HAVE AN ENJOYABLE DAY.