hello, I found on Cisco web pages, there are two kinds of E1 network module, one is NM-1CE1B=(1-port Channelized E1/ISDN-PRI balanced network module, one is NM-1CE1U=(1-port channelized E1/ISDN-PRI unbalanced network module), Can you let me know what's the difference between balanced one and unbalanced one? which one I should order? thanks, cai, land ___________________________________________________________________ 网易[电脑教程] 内容超全 下载、解疑、学习应有尽有 http://school.163.com 网易新闻频道,不但新,更要update您的判断力! http://news.163.com ___________________________________ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]