<A target="_blank" href="http://www-01.ibm.com/support/docview.wss?rs=899&context=SWA40&context=SWA50&context=SWA60&context=SWD10&context=SS4R7J&context=SSES8G&context=SSKTYF&context=SSMT72&context=SSPQ7E&context=SSMSB2&context=SS6JVW&context=SS5LUA&context=SSCM2P&context=SS3LP9&context=SSFLMV&context=SSESJN&context=SSKTPA&context=SSVHEW&context=SSVHFY&context=SSVLBW&dc=D400&dc=DB500&dc=D800&dc=D900&dc=DA900&dc=DA800&dc=DA600&dc=DB400&dc=D100&dc=D600&dc=DB600&dc=DA400&dc=DB300&dc=DA100&dc=DB100&dc=DA700&dc=DA450&q1=google+talk&uid=swg21391126&loc=en_US&cs=UTF-8&lang=all">If your Sametime Gateway uses Google Talk Federation servers</A>, you need to update the IP addresses. This is the Technote explaining it all.