Friday, November 23, 2007

SIP in time and Asterisk 1.4.14 release

The Asterisk Development Team has released the latest Asterisk version 1.4.14. This is a regular maintenance release that contains numerous bug fixes across the entire code base. A ChangeLog that lists all changes that were made is available with the release.

The release is available on downloads.digium.com. It is also available as a patch against the previous release.

A special note from ChangeLog that I found to be very importent;

Those using SIP phones should be aware that Asterisk is sensitive to large jumps in time. Manually changing the system time using date(1) (or other similar commands) may cause SIP registrations and other internal processes to fail. If your system cannot keep accurate time by itself use NTP (http://www.ntp.org/) to keep the system clock synchronized to "real time". NTP is designed to keep the system clock synchronized by speeding up or slowing down the system clock until it is synchronized to "real time" rather than by jumping the time and causing discontinuities. Most Linux distributions include precompiled versions of NTP. Beware of some time synchronization methods that get the correct real time periodically and then manually set the system clock.

Apparent time changes due to daylight savings time are just that, apparent. The use of daylight savings time in a Linux system is purely a user interface issue and does not affect the operation of the Linux kernel or Asterisk. The system clock on Linux kernels operates on UTC. UTC does not use daylight savings time.

Also note that this issue is separate from the clocking of TDM channels, and is known to at least affect SIP registrations.

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