Cisco IP Phones Daylight Savings Time (DST) Problem

Cisco’s Unified Communications Manager (CUCM) isn’t playing nice with the government-mandated changes to the start and end  dates of  Daylight Saving Time (DST) that began on Sunday morning.

CSCsy25150: CUCM timezone DST date corner case

You can read the full bug report on Cisco’s web site if you’re a member.

In short, if your phones are showing an incorrect time and your time-of-day routing is hosed, this is likely your problem.

Cisco DST Problem Workaround

Cisco gives you three options, none of which are especially good…

• ignore the problem, it’ll go away on its own March 15 (and return in November)
• assign your phones to a group called ‘DST-Workaround’ and put those devices in a timezone one hour ahead
• wait for a patch, available later this week

If you choose the group option, make sure to remove that group when you apply the upcoming Cisco Fix.

SIP Protocol Cisco Phones on Asterisk, Not CallManager

If you are using Cisco IP Phones on Asterisk (or other non-Cisco platform) and the time is wrong, your problem is likely your SIPDefault.conf file. When the government changed the start and stop dates for Daylight Saving Time, an update to the config file was required.

To fix your phones, remove all lines beginning with ‘dst_’ from your SIP config files and replace them with these…

dst_offset: 1 ;
dst_start_month: Mar ;
dst_start_day: "" ;
dst_start_day_of_week: Sun ;
dst_start_week_of_month: 2 ;
dst_start_time: 02 ;
dst_stop_month: Nov ;
dst_stop_day: ;
dst_stop_day_of_week: Sun ;
dst_stop_week_of_month: 1 ;
dst_stop_time: 2 ;
dst_auto_adjust: 1 ;

Need Additional Cisco Phone Help?

We have been using Cisco IP phones against an Asterisk system for several years now. If you need any additional assistance for new or existing installations, please contact us today.

Telephone: 561-491-5750

Email: sales@DedicatedIT.com

Or for immediate help, Chat with a Solutions Expert .

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