Configuring telnet in cisco routers

In my netork I am using main router as cisco 3845 And in client sides cisco 1841.. Some of my clients are connected through leased line and some others are BRI ISDN line. And here I am using static policy based routing. My problem is i can telnet any client routers (Cisco 1841) from PC which is situated NOC. But I cant telnet directly from my main router (Cisco 3841) Which ic located in NOC LAN.