Note that big time changes can cause issues (bug #4020)

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@5482 65c4cc65-6c06-0410-ace0-fbb531ad65f3

README

@@ -162,6 +162,23 @@ parameters.  For example, the line "channel => 25-47" creates objects for
 the channels 25 through 47 of the card, obtaining the settings
 from the variables specified above.
 
+* SPECIAL NOTE ON TIME
+  
+  Those using SIP phones should be aware the Asterisk is sensitive to large
+jumps in time. Those who live in areas that are on Daylight Savings Time (or
+equivalent) should set their system and hardware clocks to use UTC in order
+to avoid any possible jumps in system time. There should be no noticeable
+effects to the user, as you should still set your system to use the local
+offset from UTC.
+
+  Even for those who don't live in DST zones, this issue may manifest itself
+if the administrator makes large manual time adjustments. Thus, it is good
+practice to keep the time on your Asterisk server synced to a reliable
+source, such as an NTP server. 
+
+  Also note that this issue is separate from the clocking of TDM channels, and
+is known to at least affect SIP registrations.
+
 * MORE INFORMATION
 
   See the doc directory for more documentation.