show ntp love...

network time protocol

your phone system will need to have it's time sync'd and it would be a good idea for your network in general... the good folks at the free organizations request that you limit one device in your network and IOS readily obliges...

first find a supporting site...  there is this thing called google...


Name IP Address Location
nist1-ny.ustiming.org 64.90.182.55 New York City, NY
nist1-nj.ustiming.org 96.47.67.105 Bridgewater, NJ

r2620_01(config)#ntp server 64.90.182.55

r2620_01(config)#do sh ntp assoc

      address         ref clock     st  when  poll reach  delay  offset    disp

*~64.90.182.55     .ACTS.            1    54    64  377    39.5    1.83     4.4

 ~127.127.7.1      127.127.7.1       3    11    64  377     0.0    0.00     0.0

 * master (synced), # master (unsynced), + selected, - candidate, ~ configured

notice the master...

then add the other devices...

sw2950_02(config)#ntp peer 192.168.1.50

sw2950_02(config)#do sh ntp assoc

      address         ref clock     st  when  poll reach  delay  offset    disp

 ~192.168.1.50     64.90.182.55     16  1937    64    0     5.1    0.18  16000.

 * master (synced), # master (unsynced), + selected, - candidate, ~ configured

sw2950_02(config)#

notice the peer...  the world on time...