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<body><div style="text-align: left;">A little background: We installed 4.2.3 about 8 months ago as part of a pilot program and have a several sites for a total of about 80-90 phones. We will be adding our main site with approximately 400 users within the next 12 months. We have one Call Manager Cluster that is sized for all of this along with a Unity server.<br><br>Should we upgrade to the latest 5.X version and consider using SIP? Is the upgrade a painful process and is there any long term benefit? I am a little concerned about staying on the Windows platform and the proprietary SCCP protocol. At the same time, I'm concerned about the reliability of 5.X and the learning curve.<br><br>Any insight would be appreciated.<br><br>Thanks!<br></div><br /><hr />Change is good. See what’s different about Windows Live Hotmail. <a href='http://www.windowslive-hotmail.com/learnmore/default.html?locale=en-us&ocid=RMT_TAGLM_HMWL_reten_changegood_0507
' target='_new'>Check it out!</a></body>
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