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...
