[cisco-voip] 3rd-gen and newer IP phones 5-10 seconds slow

Wes Sisk wsisk at cisco.com
Fri May 8 21:19:09 EDT 2009

We have had at least one report of this before.  That issue appears 
associated to CSCsd54013.  I don't necessarily agree with that. 

My recollection (questionable?) of this issue is that when 3rd gen phone 
are provided NTP server they ignore time from CM.  If the phones cannot 
sync from NTP source for any reason then they drift.

Are you attempting to provide NTP source to the phones via any means?


On Friday, May 08, 2009 5:10:44 PM, Bill Simon <bills at psu.edu> wrote:
> Running CM 4.1.3 with NTP configured on all servers to sync to two 
> reliable NTP sources and peer with each other for verification.
> I run ntpq and check each server and all are synced up.
> My 7940s and 7960s are right on time.  But newer phones, 7961, 7965 
> and 7906 are anywhere from 5 to 10 seconds slow.
> I am aware that older phones used SCCP messages to sync time, and 
> newer phones appear to use a different method.  SIP firmware loads use 
> NTP; what do SCCP firmwares use?
> Even after a **#** reset, the phone's time is lagged.
> Is this a defect of the Java-based firmware, or do I have another 
> issue within the system causing the lag in the time displayed on the 
> newer phones?
> Bill
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